NOTE: To maintain best possible emission performance. (Date of Manufacture) 5 is the last digit in the year of manufacture (1995). The last three numbers of the specification number indicate a variation to the basic engine specification.) or the Environmental Protection Agency (E. and serial numbers or date of manufacture (D. The serial number or D.Overhead Valve Vertical Medium Frame
OHSK .P.) are stamped into the blower housing. Using model OHV16-204207A. 1 & 2). Emissionized engines that meet the California Air Resource Board (C.Overhead Valve Vertical Medium Frame Extra Life OHV . specification. 5215C is the serial number or D.Overhead Valve Vertical Rotary Mower OVXL .O. indicates the production date of the engine.Overhead Valve Vertical The number designations following the letters indicate the basic engine model.A.Overhead Valve Horizontal MediumFrame .O. OHH OHM . interpretation is as follows: OHV16-204207A is the model and specification number. or located on a decal on the engine in locations as illustrated (diag. 2). 204207A is the specification number used for properly identifying the parts of the engine.Overhead Valve Horizontal Snow King OVM OVRM . 215 indicates the calendar day of that year (215th day or August 3.M.A. C represents the line and shift on which the engine was built at the factory. serial 5215C as an example. The engine identification decal also provides the applicable warranty code and oil recommendations (diag.O. EMISSION REGULATIONS FOR ULGE ENGINES AS APPLICABLE FUEL: REGULAR UNLEADED OIL : USE SAE 30 OHV 125 203000A RTP358UIG2RA 358cc (D) 3057D
2 1
.
Interpretation of Model Number
The letter designations in a model number indicate the basic type of engine.M. OHV Overhead Valve Vertical 16 Indicates the basic engine model.R.
ENGINE MODEL NUMBER
1
THIS ENGINE MEETS 1995-1998 CALIF.) standards will include additional required engine information on the engine decal. use only Genuine Tecumseh Parts.Overhead Valve Horizontal .M.CHAPTER 1 GENERAL INFORMATION
ENGINE IDENTIFICATION
Tecumseh engine model. The number following the model number is the specification number.B. 1995).

clean.5 -17 2 1/4" filter (part # 36563) 62 1860 OHV 13. of 221000 and up.564A SER 5107
SERIAL NUMBER
FUELS
3
Tecumseh Products Company strongly recommends the use of fresh. high load applications. fuel quality is critical to engine performance.
ml.5 . NOTE: For severe. (720 ml.H.B. (Short Block Vertical). (Short Block Horizontal) or S. THIS SYMBOL POINTS OUT IMPORTANT SAFETY INSTRUCTIONS WHICH IF NOT FOLLOWED COULD ENDANGER THE PERSONAL SAFETY OF YOURSELF AND OTHERS. Be sure original container is marked: A. Never use gasoline. TECUMSEH RECOMMENDS USING ONE OF THE FOLLOWING FOUR CYCLE OILS THAT ARE SPECIALLY FORMULATED TO TECUMSEH SPECIFICATIONS. Leaded fuel is generally not available in the United States and should not be used if any of the above options are available.17 without oil filter 55 1650 OHV 13.OHSK 50-70 21 630 OVRM 40 .) (BELOW 00F (-18oC) ONLY): SAE 0W30 is an acceptable substitute. FOR WINTER (Below 320F) (0oC) USE SAE5W30 OIL. additives or stabilizers containing methanol. MTBE. FOLLOW ALL INSTRUCTIONS. or 15% ETBE may also be used. SAE10W oil is recommended. have a capacity of 26 oz. OVXL 120. Regardless of which of the approved fuels are used. HIGH QUALITY DETERGENT OIL. Using multigrade oil may increase oil consumption. PART #730225 Use SAE30 oil in high temperature. FOR SUMMER (Above 320 F) (0oC) USE SAE30 OIL. prolonged winter operation of HH120 model.
ENGINE OIL
TECUMSEH FOUR CYCLE ENGINES REQUIRE THE USE OF A CLEAN. OHSK 110* .) 2
. and promotes good starting by reducing the build up of combustion chamber deposits. or Bulletin 111. See "STORAGE" instructions in the Technician's Manual.V.I. Unleaded gasoline burns cleaner.P. or fuel blends which exceed the limits specified above for Ethanol. extends engine life. Unleaded regular. or 15% MTBE. Fuel should not be stored in an engine or container more than 30 days prior to use. white gas.13 with filter 39 1170 OHV 13. Operators Manual.SHORT BLOCKS
New short blocks are identified by a tag marked S.5 -17 2 5/8" filter (part # 36262) 64 1920 * NOTE: Model OHSK110 with a spec.
Capacities
Engine Model
Oz. part number 730245. or ETBE because engine/fuel system damage could result. This time may be extended with the use of a fuel stabilizer like TECUMSEH'S.
SBV OR SBH IDENTIFICATION NUMBER SHORT BLOCK IDENTIFICATION TAG
SBV.6. PART #730226 (SAE 10W is an acceptable substitute. unleaded regular gasoline in all Tecumseh Engines. Original model identification numbers of an engine should always be transferred to a new short block for correct parts identification (diag. unleaded premium or reformulated gasoline containing no more than 10% Ethanol. 125 32 960 OHV 11 . DO NOT USE SAE10W40 OIL. fuel conditioners.B.100 26 720 OHM.13 without oil filter 32 960 OHV 11 .
OHH. service "SF" thru "SJ" or "CD".130 32 960 OVM 120. 3).75 21 630 OVRM105 & 120 21 630 OHSK80 .

On units that the drain plug is accessible. Other units drain at the base of the engine above the deck or frame. gas tank. remove the plug and allow the oil to drain into a proper receptacle. Once the oil is drained. Further repairs may be necessary if the engine's performance remains poor. and use a spark plug wrench to turn the spark plug 1/8 to 1/4 turn further if using the old spark plug. Set the proper spark plug gap (. carburetor. Always check fuel as a primary cause of poor engine performance. OHV13. reinstall the drain plug and fill the engine with new oil to the proper capacity. If a torque wrench isnt available. fuel filter and fuel 4 line are clean. Remove the blower housing and clean all dirt. fuel line. NOTE: The oil filter (if equipped) requires changing every 100 hours or more often if operated under dusty or dirty conditions. 3
. Make sure all ignition wires are free of abrasions or breaks and are properly routed so they will not rub on the flywheel. where access to the drain plug is restricted by the equipment. 6. change the oil at least once per year. Make sure the fuel tank. 8.762 mm) and install the spark plug in the engine.Oil Change Intervals: Change the oil after the first two (2) hours of operation and every 25 hours thereafter
(OHH & OHSK50-130.
Oil Change Procedure: Locate the oil drain plug. 9. Position the equipment so the engine is level when checking the oil.
CAUTION: Remove the spark plug wire before doing any service work on the engine. 2. or 1/2 turn further if using a new spark plug. Replace any worn or damaged governor springs or linkage. When this procedure is completed.5-17 every 50 hours). When replacing the spark plug. Contact your local governing authorities to find a waste oil disposal site.
5.
TUNE-UP PROCEDURE:
NOTE: Today's fuels can cause many problems in an engines performance due to the fuels quality and short shelf life. governor levers and linkage. Reinstall the spark plug wire.030") (. grass or debris from the intake screen. Tighten the spark plug to 21 foot pounds (28 Nm) of torque. On some rotary mower applications. consult the proper parts breakdown for the spark plug to be used in the engine being serviced. or more often if operated under dusty or dirty conditions. Make sure all remote cables are properly adjusted for proper operation. Properly reinstall the blower housing. Make the proper governor adjustments and carburetor presets where required. 1. 3. start the engine. 7. it may be necessary to drain the oil by tipping the mower in a position that would allow the oil to drain out of the fill tube. On some units this plug is located below the deck
through the bottom of the mounting flange. head. screw the spark plug in as far as possible by hand. add fuel and oil as necessary.
PLUG
4.
Oil Check: Check the oil each time the equipment is used or every five (5) hours of operation. the engine should operate properly. Inspect the level and condition of the oil and change or add oil as required. See Chapter 4 under "Speed Controls and Linkage". and air cleaner assembly if removed. See Chapter 2 under "Service". Service or replace the air cleaner. STANDARD OHV CAUTION: Remove the spark plug wire before doing any service work on the engine. The following is a minor tune-up procedure. Always make sure that drain oil is disposed of properly. If the engine is run less than 25 hours per year. cylinder cooling fins.

this is a good time to do it. Gasoline can become stale in less than 30 days and form deposits that can impede proper fuel flow and engine operation. POORLY VENTILATED AREAS. Cover the spark plug hole with a shop towel. Disconnect the spark plug wire and ground the spark plug wire to the engine. Crank the engine over. Allow to completely drain and retighten the bowl nut being careful not to damage the bowl gasket when tightening. CLOTHES DRYER OR OTHER GAS APPLIANCE. the carburetor may be drained by loosening the bowl nut on the bottom carburetor one full turn. 1. To prevent deposits from forming. is by adding Tecumseh's fuel stabilizer. If "Gasohol" has been used. several times. head.
4
. part number 730245. to the gasoline. Be careful not to damage the fuel line. carburetor. 4. WHERE FUEL FUMES MAY REACH AN OPEN FLAME. Always follow the mix ratio found on the stabilizer container. Run the engine at least 10 minutes after adding the stabilizer to allow it to reach the carburetor. complete the above procedure and then put one half pint of unleaded gasoline into the fuel tank and repeat the above procedure. 3. cylinder cooling fins. grass or debris from the intake screen. Drain the carburetor by pressing upward on bowl drain (if equipped) which is located on the bottom of the carburetor bowl. or by draining the fuel tank by removing the fuel line at the carburetor or fuel tank. Install the spark plug and connect the spark plug wire. On carburetors without a bowl drain. slowly. AND AWAY FROM ANY OPEN FLAME OR COMBUSTION SOURCE. or fuel tank.STORAGE (IF THE ENGINE IS TO BE UNUSED FOR 30 DAYS OR MORE)
CAUTION: NEVER STORE THE ENGINE WITH FUEL IN THE TANK INDOORS OR IN ENCLOSED. WATER HEATER.
Change Oil: If the oil has not been changed recently. 2. If Gasohol is allowed to remain in the fuel system during storage. the alcohol content can cause rubber gaskets and seals to deteriorate. Remove all gasoline from the fuel tank by running the engine until the engine stops. all gasoline must be removed from the fuel tank and the carburetor.
Oil Cylinder Bore
1.
Draining the Fuel System
CAUTION: DRAIN THE FUEL INTO AN APPROVED CONTAINER OUTDOORS. SPARK OR PILOT LIGHT AS ON A FURNACE.) of clean engine oil into spark plug hole. fittings. 2. See "Oil Change Procedure" on page 3. Fuel stabilizer is added to the fuel tank or storage container. Remove the spark plug and put a 1/2 ounce (15 ml. governor levers and linkage. An acceptable alternative to removing all gasoline. Clean Engine: Remove the blower housing and clean all dirt. 3. BE SURE THE ENGINE IS COOL.

In Tecumseh's Kleen Aire® system. Snow King® engines do not use an air filter due to the clean operating environment and to prevent filter freeze-up. The flocked screen is used as an additional filter on XL or XL/C engine models that use a polyurethane filter element. Pre-cleaners or flocked screens provide more air cleaning capacity.
AIR CLEANER BODY
FLOCKED SCREEN
1
COVER
COMPONENTS
The cover holds the filter element and prevents large debris from entering the filter body. The paper or polyurethane filter element is the main filter to trap dust and dirt.
KLEEN-AIRE® ENTRANCE FROM UNDER BLOWER HOUSING
POLYURETHENE WRAP
PAPER ELEMENT
AIR CLEANER BODY
2
5
. and the polyurethane or paper filter element. A polyurethane precleaner or a flocked screen may be used with the main filter.
COVER
KLEEN-AIRE® ENTRANCE FROM UNDER BLOWER HOUSING
FOAM ELEMENT
OPERATION
The air cleaner cover allows access to the air filter element(s) and prevents large particles from entering the filter body. Filtered air is necessary to assure that abrasive particles are removed before entering the combustion chamber. The polyurethane wrap pre-cleaner is used on XL or XL/C engine models with paper filter elements. air is drawn in through a rotating screen or recoil housing to be centrifugally cleaned by the flywheel before the air enters the air filter. Dirt allowed into the engine will quickly wear the internal components and shorten the life of the engine. Tecumseh engines use either a polyurethane or a paper-type air filter system.CHAPTER 2 AIR CLEANERS
GENERAL INFORMATION
The air cleaner is the device used to eliminate dust and dirt from the air supply. Dry-type paper elements are pleated paper for increased surface area and rubberized sealing edges. Air is filtered through the pre-cleaner or flocked screen if equipped. The polyurethane filter uses an oil film to trap fine particles found in dust. Extremely dirty conditions may require more frequent filter cleaning or replacement.

whichever comes first. Extremely dirty or dusty conditions may require daily cleanings. starts smoking abnormally. 3. make sure the seam is installed to the outside to prevent gaps between the paper element and the pre-cleaner. more often if used in extremely dusty conditions. 6. Clean the excess contaminants out of the air cleaner body before removing the old element. A dirt restricted or an oil soaked filter will cause noticeable performance problems. remove the air cleaner assembly from the carburetor before removing the flocked screen. 2. 8.
SERVICE
Service on the polyurethane filter element (cleaning and oiling) is recommended every three (3) months or every twenty five (25) operating hours. This prevents dirt from entering the carburetor (diag 3). A paper-type air filter should only be replaced. ALWAYS REPLACE THE FILTER ELEMENT WITH THE PROPER TECUMSEH ORIGINAL REPLACEMENT PART. On air cleaners that use a flocked screen under the polyurethane element. The paper filter element should be replaced once a year or every 100 operating hours. A polyurethane filter may be cleaned following the service procedure listed under "Service" in this chapter. When installing the polyurethane pre-cleaner.
KLEEN-AIRE® ENTRANCE FILTER A (FOAM)
WING NUTS
COVER
GASKET NUTS
FILTER B
BODY
COVER GASKET
FOAM FILTER KLEEN-AIRE® ENTRANCE FLOCKED SCREEN
GASKET
3
6
. remove the old gasket between the carburetor and the air cleaner assembly. Reinstall the air cleaner assembly using a new gasket. the first engine component to be checked is the air filter.TROUBLESHOOTING OR TESTING
If the engine's performance is unsatisfactory (needs excessive carburetor adjustments. Use reverse procedure for reassembly. New nuts are supplied with a new filter and are to be used for proper sealing. Clean the inside of the cover and body. loses power). A paper-type filter cannot have an oil film present on the paper. 5. Unlock the tabs or remove the screws or wing nuts holding the air cleaner cover in place.
DISASSEMBLY PROCEDURE
1. 4. 7. Follow the procedure listed in the "Service" section of this chapter for filter replacement or cleaning. NOTE: NEVER RUN THE ENGINE WITHOUT THE COMPLETE AIR CLEANER ASSEMBLY INSTALLED ON THE ENGINE. Remove the old element and the polyurethane pre-cleaner if equipped. Remove the hex nuts holding the element down if equipped.

Paper -type filter element
Paper type air filter elements can only be serviced by replacement. 5). Wash the filter or precleaner in a detergent and water solution until all the dirt is removed. On the polyurethane filter only. Replacement filters are available at any authorized Tecumseh Service Outlet. re-oil the filter by applying engine oil and squeezing it vigorously to distribute the oil. Rinse in clear water to remove the detergent solution. it should be replaced with a new screen. Be sure to use new filter nuts or seals for the air cleaner studs if supplied with the new filter (diag. Clean the air cleaner housing and cover being careful not to allow dirt to fall into the carburetor or intake pipe.Polyurethane-Type Filter Element or pre-cleaner
This type of air filter or pre-cleaner can be serviced when restricted with dust or dirt. Roll the filter in a cloth and squeeze it (do not twist) to remove the excess oil.
Flocked Screen
A flocked screen may be cleaned by blowing compressed air through the screen from the backside. Do not attempt to clean a paper filter element.
COVER
COVER
KLEEN-AIRE® ENTRANCE FROM UNDER BLOWER HOUSING
FOAM ELEMENT
POLYURETHENE WRAP
PAPER ELEMENT
AIR CLEANER BODY
AIR CLEANER BODY
FLOCKED SCREEN
4
KLEEN-AIRE® ENTRANCE FROM UNDER BLOWER HOUSING
5
7
. The pre-cleaner must not be oiled. Squeeze the filter or pre-cleaner (do not twist) to remove the excess water. If the screen cannot be cleaned with this procedure. Wrap the filter or pre-cleaner in a clean cloth and squeeze it (do not twist) until completely dry.

ALTERNATE LOCATION FOR MANUFACTURING NUMBER
89 4
MANUFACTURING NUMBER
F5
89
4F5
CARBURETOR DATE CODE
1
OPERATION
In the CHOKE or START position. A fuel / air mixture is supplied through the primary idle-fuel discharge orifice during idle. a second orifice is uncovered as the throttle shutter opens. Carburetors used by Tecumseh can be identified by a manufacturing number stamping on the carburetor as illustrated (diag. the throttle shutter is opened. Air flows through the carburetor at high speed. During INTERMEDIATE engine operation. a relatively small amount of fuel is required to operate the engine. Since the majority of the air passage is blocked by the choke shutter. The venturi. or nonadjustable. Some Tecumseh engines utilize Walbro carburetors. Higher pressure (atmospheric air) rushes into the engine to fill the created low pressure area. An alternate method to find the correct carburetor part number is to use the manufacturing number stamped on the carburetor and convert this number to a service part number. The carburetor fuel mixtures are either fully adjustable. use the engine model and specification number to obtain the correct carburetor part number. further accelerates the air flow. As the starting device is operated to start the engine. and related fuel system service is covered in this chapter. Basic operation is very similar to the Tecumseh float style carburetor. Float type carburetors use a hollow float to maintain the operating level of fuel in the carburetor. and more fuel mixture is allowed to atomize with the air flowing into the engine. 8
.
CHOKE PLATE
FLAT DOWN
2 At engine IDLE speed. An instruction sheet is provided with the new service carburetor or see SERVICE in this chapter. a cross reference chart will convert a carburetor manufacturing number to a Tecumseh Service part number. A maximum fuel flow through the carburetor orifices combined with the reduced quantity of air that passes through the carburetor. and the only air entering the engine enters through openings around the shutter. The main nozzle and both idle fuel discharge ports are supplying fuel due to the low air pressure in the intake of the engine. which decreases the size of the air passage through the carburetor. Carburetor adjustments. A standard service carburetor is a basic carburetor that may require the use of original carburetor parts or additional new parts to adapt to the specification. cleaning. partially adjustable. downward piston travel creates a low air pressure area in the engine cylinder above the piston. The float type carburetor will have a fuel enrichment system of either a primer or a manual choke to provide easy cold engine starting.CHAPTER 3 CARBURETORS AND FUEL SYSTEMS
GENERAL INFORMATION
Tecumseh overhead valve engines use float type carburetors. When servicing carburetors. make a very rich fuel mixture which is needed to start a cold engine. Fuel is forced out the main nozzle opening due the difference in the atmospheric air pressure on the fuel in the carburetor bowl and the reduced air pressure at the main nozzle opening. 1). This high speed movement of the air decreases the air pressure at the main nozzle opening. The throttle is almost completely closed. In the carburetor section of the Master Parts Manual or Microfiche Catalog. During HIGH SPEED engine operation. a relatively small quantity of air enters the carburetor at increased speed. the choke shutter is closed. Complete carburetor replacement may be accomplished by a standard service carburetor.

it raises the float.
VALVE CLOSED ATMOSPHERIC VENT
CARBURETOR FITTING VALVE OPEN DIAPHRAGM FILTER AIR BLEED VALVE OPEN FUEL SUPPLY VALVE CLOSED
PULSE LINE TO CRANKCASE
FLOW DIRECTION á SUCTION FUEL PRESSURE ATMOSPHERIC ê CAUSED FUEL FLOW
êCRANKCASE PRESSURE á ATMOSPHERIC PRESSURE ACTING ON DAMPING DIAPHRAGM á FUEL FLOW
ê CRANKCASE SUCTION AND FLOW DIRECTION á
ATMOSPHERIC PRESSURE ACTING ON DAMPING DIAPHRAGM
6
FLOAT STYLE CARBURETORS
A float is used to maintain the operating level of fuel in the carburetor bowl. The vent allows atmospheric air to enter the fuel bowl during operation and to fill the primer bulb after the primer bulb is released. 6).
IDLE AIR BLEED
MAIN AIR BLEED CHOKE SHUTTER
THROTTLE SHUTTER
IDLE ADJUSTMENT
INLET NEEDLE AND SEAT
FLOAT MAIN NOZZLE MAIN ADJUSTMENT
7 9
. 7). Some internally vented float style carburetors use a tygon tube and a vent within the air intake. When the needle contacts the seat.
TYGON TUBE INTERNAL VENT EXTERNAL VENT
3
FUEL PRIMERS
Primers may be mounted remotely or as an integral part of the carburetor. Fuel flows by gravity or a pulse pump into the fuel bowl. Impulse fuel pumps are operated by crankcase impulses created by the up and down movement of the piston. This tube must be present for the carburetor to operate properly (diag.
PRIMER BULB VENT PRIMER BULB
MAIN NOZZLE
4
MAIN JET
5
IMPULSE FUEL PUMPS
Impulse fuel pumps may either be mounted externally onto the carburetor fuel inlet or remotely mounted. The float height is set according to the service procedure. Primers must be vented either internally through a passage in the carburetor air horn prior to the venturi or externally through a hole in the primer bulb. the fuel flow is stopped. This displaced fuel provides a rich mixture necessary for engines to start easily on the first or second attempt (diag. As the fuel level in the bowl again rises. Atomization occurs as the fuel mixture contacts the fast moving air stream and the mist flows into the intake of the engine. The impulses actuate the diaphragm and flap valves to lift the fuel from the fuel tank to the carburetor (diag. Air is bled into the main nozzle through the air bleed located in the air horn. the carburetor bowl must be either vented externally or internally. This upward float motion moves the inlet needle valve to the closed position. the fuel level in the carburetor bowl drops and the float moves downward. This mixes fuel and air prior to the fuel leaving the main nozzle. 3). The basic function of the primer is to supply an air pressure charge to the carburetor main well or carburetor bowl to displace fuel directly into the carburetor venturi. As the fuel is used by the engine. This allows the inlet needle valve to move off the sealing seat. 4 & 5). A hose called a pulse line connects the fuel pump diaphragm chamber to the crankcase and transmits the impulses to the pump diaphragm. This pump is connected in the fuel line between the fuel supply and the carburetor or directly to the fuel inlet. A crankcase overfilled with engine oil can affect pump operation.For the fuel to flow. The tapered end of the inlet needle varies the fuel flow rate and the fuel level in the carburetor bowl remains constant (diag.

8). Series 3 will have one throttle plate screw (diag. 9). The quickest way to identify these carburetors is by the presence of bosses on each side of the idle mixture screw (diag. 10). A remote primer or choke may also be used with this carburetor (diag. The die cast carburetor body is similar in appearance and slightly longer than the Walbro LMK body. (diag. This float style carburetor has a smaller venturi than the Series 3 or 4 carburetor and has no bosses on each side of the idle mixture screw. The carburetor base is flat to accept a Vector style bowl that is held on with a wire bail. The choke shaft is made of a plastic material with an internal slot to hold the choke shutter. 13) 13
10
.CARBURETOR VISUAL IDENTIFICATION
Series1 Carburetors
Series 1 carburetors are used on some 4 .7 model overhead valve engines. To determine whether the carburetor is a Series 3 or Series 4. Series 6 carburetors are commonly used on rotary mower applications. The main and idle mixture may be fixed or adjustable. Series 6 are nonadjustable. with a stepped primer bulb and a bowl prime system (diag. The Series 4 will have two throttle plate screws (diag.
12
Series 7
Series 7 carburetors are totally nonadjustable.
10
9
11
Series 6 Carburetors
Series 6 carburetors are used on 2 and 4-cycle engines in the 3 to 6 model range.
8
Series 3 & Series 4 Carburetors
Series 3 or 4 carburetors are generally used on 8 through 14 model 4-cycle engines. Series 6 uses a simple fixed idle and fixed main fuel circuit. 12). look at the throttle end of the carburetor. 11).

Also visible is a plastic main fuel discharge nozzle in the venturi. This carburetor has a fixed. 14)
CAPPED FIXED IDLE JET
CAP
14
Series 9
Series 9 carburetors are hybrid versions of the Series 8. The bowl nut uses a ball plug on the bottom to cover the center drilling. These carburetors are totally nonadjustable. Servicing should be done by a Authorized Tecumseh Dealer. Distinguish this carburetor from the Series 6 by the fixed idle jet that appears as a screw just above the bowl on the primer side. with the added benefit of a choke for cold weather starting. Idle mixture screws were adjustable on early production OHV15. This series of carburetor uses an integral primer system like the Series 6. This carburetor uses a fixed idle jet and fixed main fuel circuit. It has a fixed main and idle with a serviceable main nozzle and a primer assist. The carburetor is attached to the intake pipe using studs that also fasten the air filter body.Series 8
Series 8 carburetors have both a fixed main and a fixed idle circuit. This carburetor is totally nonadjustable. It is the equivalent of the series "8" with the addition of a choke. 15)
MIXING WELL CAST BUT NOT MACHINED
IDLE JET CAST BUT NOT MACHINED
15
CHOKE PLATE
Series 10
This carburetor is for use on all season engine applications. nonadjustable main mixture jet. Walbro model and manufacturing numbers are found on the throttle end of the carburetor.
LOW IDLE MIXTURE SCREW MAY BE ADJUSTABLE OR FIXED
16
11
. (diag. This fixed idle jet may also be capped.
FLAT SIDE DOWN
15
Walbro Model LMK
OHV 15-17 models use this float-feed carburetor. The Idle mixing well and jet will be visible but not machined (diag. If no spring is visible. the jet is fixed. This has since changed to a fixed idle jet which may be capped for tamper resistance.

Replace the spark plug if questionable. the carburetor will need to be removed for service. 17). Check the throttle control bracket for proper adjustment allowing a full choke shutter position. Install the spark plug and high tension lead and try to start the engine. air filter replaced or clean). If the carburetor is functioning properly the problem may be ignition timing related.
SERVICE
Carburetor Pre-sets and Adjustments
Before adjusting any mixture screws the necessary carburetor presets should be made. Replace the air filter if restricted or oil soaked. A wet spark plug indicates fuel is being supplied by the carburetor. excessive choking or over priming. See Chapter 9 under Troubleshooting.
PLUG
3. remove the fuel line clamp on the carburetor fuel inlet and pull the fuel line off the fitting. Always check fuel as a primary cause of engine performance. and a known good functional carburetor indicates an internal engine problem exists. check for spark by removing the high tension lead and removing the spark plug. Improper fuel flow indicates the fuel.
17 CAUTION: DRAIN THE FUEL INTO AN APPROVED CONTAINER OUTDOORS. If no or irregular spark see Chapter 8 under "Testing". proceed to step 2. 8. or air cleaner assembly if applicable to visually check that the choke shutter completely closes or check to see if fuel comes out of the main nozzle during priming. the carburetor will require service.TESTING
1. Start the engine and allow it to warm to operating temperature.M. Check the engine compression using a commercially available compression tester and follow the testers recommended procedure. If the fuel flow from the tank is adequate and no fuel is evident during priming. 6. carbon shorted or defective spark plug. With a proper draining receptacle. See Chapter 4 under "Speed Controls and Linkage". 2. continue with step # 7. After repeated efforts to start the engine using the procedure listed in the operators manual fail. Consult microfiche card #30 to find the correct R.
4. Check to see if the normal maintenance procedures have been performed (oil changed. adequate fuel flow. 5. 9. With the spark plug removed and a shop towel over the spark plug hole. CHECK THE FUEL CAP FOR PROPER VENTING. Visually inspect the removed spark plug for a wet condition indicating the presence of gasoline in the cylinder. Check for the proper governor adjustments as outlined in Chapter 4. If the engine floods and fails to start. If the spark plug is wet. settings for the engine. AVOID THE SPRAY FROM THE SPARK PLUG HOLE WHEN CRANKING THE ENGINE OVER. AND AWAY FROM ANY OPEN FLAME OR COMBUSTION SOURCE. filter or tank require cleaning or replacement. STANDARD OHV NOTE: Check plug for correct reach (diag. heater box. Install a commercially available spark tester and check for spark. NOTE: Todays fuels can cause many problems in an engines performance. If the spark plug is dry. a dry spark plug. fresh fuel. If the spark is bright blue and consistent. Remove the air filter. 7. 12
. Examine the fuel flow with the fuel cap both on and off the fuel tank. due to the fuels quality and short shelf life. The carburetor can now be adjusted. See the proceeding Carburetion Troubleshooting chart for additional causes. The engine may be flooded by a restricted air filter. fuel line. See Chapter 8 Ignition under Troubleshooting. NOTE: RPM SETTINGS CAN ALSO BE FOUND ON THE COMPUTERIZED PARTS LOOK UP SYSTEMS. BE SURE THE ENGINE IS COOL.P. check for restrictions in the fuel system before the carburetor. Low compression. Identify the correct carburetor model and manufacturer to find locations of the high and low speed adjustment screws. See Service in this chapter or consult the Carburetion Troubleshooting chart to diagnose carburetor symptoms. improperly adjusted or defective carburetor. CAUTION: KEEP ALL COMBUSTIVE SOURCES AWAY. turn the engine over slowly 3 or 4 times to remove excess gasoline from the engine cylinder.

Tecumseh Carburetors Engine Model Main Pre-set Idle Pre-set 1 turn
All models with float-type carburetors 1-1/2 turn All models with diaphragm-type carburetors Carburetor Model LMK
1 turn
1 turn
Walbro Carburetors Fixed 1 turn if adjustable or seated.Pre-sets and Adjustments (Tecumseh and Walbro carburetors)
Turn both the main and idle mixture adjusting screws in (clockwise) until finger tight if applicable. IDLE MIXTURE FIXED JETS APPEAR AS ADJUSTING SCREWS WITHOUT TENSION SPRINGS AND ARE NOT ADJUSTABLE.
TECUMSEH CARBURETORS
DUAL SYSTEM / SERIES "6" SERIES "7" SERIES "3" & "4"
NON-ADJUSTABLE PRIMER NO CHOKE
18
FIXED HIGH AND LOW SPEED MIXTURE
19
IDLE MIXTURE SCREW
MAIN MIXTURE SCREW
WALBRO CARBURETOR
SERIES "8" SERIES "9" SERIES "10" WALBRO LMK
20
CAPPED FIXED IDLE JET
NON-ADJUSTABLE (ADJUSTABLE MAIN FOR EXPORT)
21
NON-ADJUSTABLE
22
23
24 13
. NOTE: RPM SETTINGS CAN ALSO BE FOUND ON THE COMPUTERIZED PARTS LOOK UP SYSTEMS. if fixed
Final Adjustments
Start the engine and allow it to warm up to normal operating temperature (3 . Set the speed control to the IDLE or SLOW position. Turn the screw in (clockwise) midway between these two positions. setting according to microfiche card # 30 and adjust the engine speed accordingly. Note the position of the screw. turn the screw out (counterclockwise) until the engine begins to run erratic. IDENTIFY THE SERIES OF CARBURETOR USING THE VISUAL IDENTIFICATION IN THIS CHAPTER.M. NOTE: SOME CARBURETORS HAVE FIXED IDLE AND MAIN JETS. then locate the recommended HIGH and LOW R. Now back the mixture screws out (counterclockwise) to obtain the pre-set figure in the chart shown. then turn the main mixture adjustment screw in (clockwise) slowly until the engine begins to run erratic. NOTE: OVERTIGHTENING WILL DAMAGE THE TAPERED PORTION OF THE NEEDLE.P. Set the speed control to the HIGH or FAST position. Identify the location of both HIGH and LOW speed adjustments. Adjust the idle mixture screw following the same procedure used to adjust the main mixture adjustment screw.5 minutes). Now. This will be the best setting.

Remove the throttle shutter. 7. 5. until this condition is corrected. and inlet needle. until this condition is corrected. 25). move the speed control to the IDLE or SLOW position. The cap is removed by piercing it with an ice pick or similar instrument. throttle shaft.
3/32" (2.38 mm)
LONG END OF CLIP
CLIP OPEN END OF CLIP THROTTLE END
CHOKE END
25
26
27
14
. After the main mixture screw is set. Note or mark the high and low mixture adjusting screws to aid in reassembly (if applicable). (diag. Remove the bowl drain screw and gasket. On Series 7 carburetors. Remove the idle mixture screw assembly. testing each setting with the equipment under load. grasp the crossbrace on the float with a needlenose pliers and pull straight out to release the float hinge pin. setting and adjust as necessary. If the engine does not idle smoothly.
CARBURETOR DISASSEMBLY PROCEDURE
NOTE : CARBURETORS THAT ARE EMISSION COMPLIANT (MANUFACTURING NUMBERS 5000 OR GREATER) WITH FIXED IDLE OR MAIN JETS ARE TO BE REMOVED BY DEALERS ONLY FOR INSPECTION AND CLEANING. Remove the spring. turn the main adjusting screw in (clockwise) 1/8 turn at a time. release the wire retainer that retains the bowl and remove the bowl assembly. Walbro model LMK uses a non-serviceable seat). 3. If the engine smokes excessively (rich).38 mm) hook end (Tecumseh carburetors only. metering jet. then remove the jet for service. Remove the float. springs and choke shaft by removing the screw or screws that attach the throttle or choke shutter to the shaft inside the air horn. Recheck the high and low R. bowl nut. Remove the inlet needle seat using a wire or a paper clip with a 3/32" (2. remove the main nozzle tube. THE SHUTTERS HAVE BEVELED EDGES AND MUST BE INSTALLED IN THE ORIGINAL POSITION.M. 6. A few Tecumseh carburetors were built as air adjust idle system.If further adjustment is required. and spring located in the center leg of the carburetor bowl. and float bowl. the adjustments are reversed out for lean in for richer. Push the hook through the hole in the center of the seat and pull out to remove it. To remove the choke shaft assembly on Series 7 or Walbro LMK carburetors. carefully move the retainer to prevent bending of the wire. choke shutter. Note the position of the hooks before removing the float hinge pin (diag. Some carburetors use a float dampening spring to aid the inlet valve to maintain a steady position in rough service applications.P. Note or mark the action of the choke and throttle shutters and the hook points of the choke or throttle return spring or seal retainer springs located on the top of the choke or throttle shaft. On Series 7 only. always replace the cap. If you have one. Slide the choke shaft out of the carburetor body. 1. "O" ring. 2. If a screwdriver or similar tool is used to release the retainer. turn the main mixture adjusting screw out (counterclockwise) 1/8 turn at a time. over the fixed idle jet. testing each setting with the equipment under load. clip. Remove the high speed mixture screw. the main adjustment should be made under a load condition. Remove the float hinge pin with a needlenose pliers. On Series 7 carburetors. Note the position of the spring clip on the inlet needle and float. 21). grasp the choke shutter with a pliers and pull it through the slot in the choke shaft. If the engine stops or hesitates while engaging the load (lean). Series 8 carburetors have a tamper resistant cap. and "O" ring. turn the idle mixture screw 1/8 turn either in (clockwise) or out (counterclockwise) until engine idles smoothly. 4. NOTE: MARK THE EDGES OF THE THROTTLE AND CHOKE SHUTTERS PRIOR TO DISASSEMBLY.

Remove the primer bulb (if equipped) by grasping with a pliers and pulling and twisting out of the body. Remove the retainer by prying and lifting out with a screwdriver. Remove all welch plugs if cleaning the carburetor. Impluse 2 . Note or mark the pump body alignment. 7.175 mm) CARBURETOR WIDE BODY OR CHANNEL SMALL CHISEL REDUCER 29
BALL PLUG IDLE FUEL PASSAGE REDUCTION ROD INSIDE
30
HIGH SPEED JET
31
Impulse Fuel Pump
The valve type impulse pump can be serviced using the following procedure. The Walbro LMK carburetor main fuel jet can be removed only if the jet is damaged or if a high altitude jet is needed to be installed. To remove place the carburetor firmly in a soft jawed vice. 9. thread the bolt into the shank. Pump 3 . Pump 4 . Air
6 3 9
32 15
. Install new valves with the face of the valve facing the raised portion of the passage. use 1/4"-20 bolt and nut inserted into a 1/4" (6.16 inch pounds (1. Insert the high altitude jet in the same hole. If necessary the inlet fitting can be removed by pulling with a pliers or vise. 1. The parts can only can be assembled one way without damage. 31). Note the direction of the inlet fitting. Install the diaphragms against the center portion of the body with the gaskets against the outside covers.*Gasket. Using a punch slightly larger than the diameter of the new jet. 1-1/4" (4) 10 .Bearing. 3. 2. cut off the extended portion of the valves. Install new filter in pump cavity if applicable.36 .Screw. 8. 29).
11 1 10 4 7
11
5
2
8
1 .*Diaphragm.8. Using a punch the same size or slightly smaller than the jet. After installation. 4. Pump (2) 9 .Body.Cover.700 mm) nut. Secure the carburetor in a vise equipped with protective jaws. Remove the gaskets. diaphragms. and torque the screws to 12 . 28). Pressure 11 . Pump Cover 7 . 29). Remove the old filter on the back of the pump body if applicable. 5.*Spring. Use a small chisel sharpened to a 1/8" (3. tap it into place flush with the outside of the center leg casting (diag. Check (2) 6 . NOTE: DO NOT REMOVE ANY BALL OR CUP PLUGS (diag.*Filter.81 Nm). 11. Install the spring bearing on the new spring and place into position. Assemble the body sections.175 mm) wide wedge point. Clean the body parts with solvent. Tap a 1/4-20 thread inside the metal shank.
SMALL CHISEL PRY OUT PLUG WALBRO LMK SERIES DO NOT REMOVE PLUGS ATMOSPHERIC PIERCE PLUG BRASS OR BALL PLUG VENT WITH TIP WELCH PLUG TO BE REMOVED
DO NOT ALLOW CHISEL POINT ABOUT 1/8" TO STRIKE (3. drive the jet through and into the center leg.
28
10. and thread the nut down to pull out the shank. Do not reuse old bulb or retainer (diag. The fitting must be replaced. 9.1.Body. do not twist. remove the four screws and disassemble the pump. old valves and spring bearing from the spring. Spring 5 .350 mm) flat washer and 1/2" (12. 6.*Valve. install the retaining screws. Drive the chisel into the plug to pierce the metal and push down on the chisel to pry the plug out of the hole (diag.

depending on the application (diag. Any excessive wear in these areas can cause dirt to enter the engine and cause premature wear. Bowl nuts that are used on adjustable main. Replace the O ring seal if removed (diag. then return the bowl to its original position and tighten the bowl nut. and replace if worn or damaged.
FLOAT FLOAT HINGE AND AXLE FLOAT SETTING
11 / 64" (4. This difference relates to calibration changes of the carburetor. adjust the height by bending the tab accordingly. and carburetor body at the bearing points and holes into which the linkage is fastened. replace the needle. Turn the bowl 1/4 inch in either direction.
Idle and High Speed Mixture Adjusting Screw
Examine the idle mixture needle tip and tapered surface for damage. The fuel inlet ports must be free of any debris to allow proper fuel flow.36mm) diameter drill bit across the top of the carburetor casting on the opposite side and parallel to the float hinge pin. the welch plugs must be removed to expose the drilled passages. 16
IDLE FUEL FUELTRANSFER INLET FUELPASSAGE METERING PORT ONE-HOLE TYPE TW0-HOLE TYPE
35
. or when the fuel tank is filled for the first time. Examine the tapered surface of the high speed mixture needle. To check the float setting. If the required adjustment is minor. and "O" ring.FLOAT ADJUSTING PROCEDURE
All Tecumseh carburetors with an adjustable float require the correct float height to achieve the proper operation and easy engine starts. If either is worn or damaged. use compressed air and soft tag wire or monofilament fishing line to clean internal carburetor passages. hold the carburetor in an upside down position.
Inspection
After careful disassembly of the carburetor and the removal of all non metallic parts. If dust seals are present. the tab adjustment may be made without removing the float and carefully inserting a small bladed screwdriver to bend the tab.
"O" RING BRASS WASHER SPRING HIGH SPEED ADJUSTMENT SCREW
RETAINER NUT
34
Fuel Bowl Retaining Nut
The bowl nut contains the passage through which fuel is delivered to the high speed and idle fuel system of the carburetor. check the seal condition and the correct placement next to the carburetor body. or commercial carburetor cleaner. If the float is too high or too low.
Throttle and Choke
Examine the throttle and choke shaft. THE TECUMSEH SERIES 7 AND THE WALBRO MODEL LMK CARBURETOR HAVE A FIXED AND NONADJUSTABLE FLOAT HEIGHT. To perform a proper carburetor rebuild. If the tapered surface is damaged or shows wear. The tip and tapered surface of the needle must not show any wear or damage. Tension is maintained on the screw with a coil spring. 34). no longer than 30 minutes. The float must just touch the drill bit when the bit is flush with the edge of the float. float bowl.36 mm)
ADJUSTING TAB
INLET NEEDLE AND SEAT
33
If float sticking occurs due to deposits. all metallic parts should be cleaned with solvent. Remove the bowl nut. NOTE: DO NOT INTERCHANGE BOWL NUTS. Place an 11/64" (4. If a problem occurs with the idle system of the carburetor. Wearing eye protection. 35). examine the small fuel passage in the annular groove in the bowl nut. This passage must be clean for the proper transfer of fuel into the idle metering system. float style carburetors may use either one or two metering ports. replace the adjusting needle. this condition can be quickly corrected by loosening the carburetor bowl nut one full turn.

6. it is important that the lines. Insert the throttle lever assembly into the carburetor body with both tangs of the return spring on the left side of the center boss (viewed from throttle end) and the flat side of the shaft toward the carburetor mounting flange. 4. Check for binding by rotating the throttle shaft. Install the throttle shutter to the throttle shaft using notes or marks to place the shutter as originally found (Series 7 must have the line on the shutter at the 3 o'clock position) (diag. then retighten the screws (diag. 9 carburetors. If binding occurs. With a punch equal to the size of the plug hole. (diag.
THROTTLE PLATE
THROTTLE LEVER TWELVE O'CLOCK POSITION
42
THREE O'CLOCK POSITION
43
DUST SEALS
SERIES 7
44
THROTTLE LEVER THROTTLE PLATE
WALBRO LMK SERIES
45
18
. install the throttle return spring on the throttle shaft with the squared end up. Place the welch plug into the receptacle with the raised portion up.
FLAT END PUNCH NEW WELCH PLUG SAME OR LARGER DIAMETER OF PLUG HOLE
41
Throttle Shaft and Plate
When reassembling Tecumseh or Walbro carburetors. secure the carburetor in a vise equipped with protective jaws. and 7 carburetors. then tighten the throttle shutter screws. adjust the throttle shutter by loosening and repositioning the shutter.ASSEMBLY PROCEDURE
Welch Plugs
To install a new welch plug after cleaning the carburetor. merely flatten the plug. correct by loosening the screws and repositioning throttle plate. lettering. Apply light downward pressure on the throttle shaft and rotate it clockwise to seat the throttle shutter in the bore. Do not dent or drive the center of the plug below the top surface of the carburetor. 44). 45). Test the operation of the throttle and return spring if equipped. Install the screws so they are slightly loose. If necessary. 41). New Tecumseh screws are treated with dry-type adhesive to secure them in place. Always use a new screw(s) when reinstalling the throttle shutter to prevent the screws from loosening and being drawn into the engine. If the throttle plate has only one line. Always use new throttle shutter screws when reinstalling. or numbers on the throttle plate are facing out when in the closed position. this line should be positioned in the 3 oclock position on Series 3. NOTE: NEVER REUSE OLD SCREWS. 42 & 43). Slide the foam dust seal over the spring. On Walbro LMK and Series 7 carburetors. and at the 12 o'clock position on Series 1. 8. After installation of the welch plug. seal the outer diameter with fingernail polish (diag.

and are not adjustable. install the choke return spring on the choke shaft with the squared end up and hooked into the notch in the plate. The choke shaft and plate must be in the closed position prior to tightening the screws. Test the operation of the choke and return spring function if equipped (diag.
49
FLOAT HINGE PIN FLOAT
NEEDLE & SEAT SEAT RETAINING RING
MAIN NOZZLE EMULSION "O" RING
GROOVE POSITIONED IN
SPRING IDLE RESTRICTION BOWL "O" RING MAIN JET MAIN JET SPRING GASKET BOWL DRAIN BOWL RETAINER
50 19
. Use a bench vise or press to install the fitting squarely. 47). Place a new gasket on the drain screw and tighten in position (diag. insert the tip into the carburetor body. (diag. On Series 7carburetors. Turn the high speed adjustment screw into the bowl nut and the low speed mixture screw into the carburetor body (diag. Make sure the tabs on the shutter lock the choke shaft between them. NOTE: NEVER REUSE OLD SCREWS. 31 page 15). Main Nozzle
When reassembling. Support the carburetor body with a wood block to avoid damage to other parts. Apply oil to the main nozzle "O" ring and push the main nozzle into the cavity with the "O" ring end in first. Note the cutout position of choke shutter if applicable. Rotate the shaft counterclockwise until the tang on the spring rests against the left side of the center boss on the carburetor body (viewed from choke end) . position the coil spring on the adjusting screws. 50). Place the spring over the shoulder on the main jet and push the jet into the cavity with the main jet toward the "O" ring. Rotate the shaft and check for binding.Choke Shaft and Plate
The choke plate is inserted into the air horn of the carburetor in such a position that the flat surface (if applicable) of the choke is down. place the main nozzle spring into the main nozzle cavity. the choke must return to the open position when released (diag. Work the dust shield up around the spring and insert the choke shaft into the carburetor body. the main jet can be replaced by pressing it into the center leg of the carburetor until flush. Hard starting may be due to insufficient choking action because of a misaligned choke plate. On Walbro LMK and Series 7 carburetors. CONSULT BULLETIN 110. 46). 49). 48). Rotate the choke shaft approximately 1/4 turn counterclockwise and insert the choke shutter into the slot in the choke shaft. Correct by readjusting the choke plate to close completely. Press it in until it bottoms out (diag. Choke plates will operate in either direction. Next install the "O" ring in the main jet cavity. Make sure it is assembled properly for the engine. On Walbro LMK carburetors.
CHOKE PLATE
FLAT DOWN
46
SPRING HOOKUPS
Þ
47
PRESS IN PARTIALLY THEN APPLY LOCTITE SOME INLET FITTINGS STRAINER
Fuel Inlet Fitting
When installing the fitting.
48
RETAINER NUT
"O" RING BRASS WASHER SPRING HIGH SPEED ADJUSTMENT SCREW
High and Low Speed Adjusting Screw. Always use a new screw(s) when reinstalling the choke shutter as the screws are treated with dry-type adhesive to secure them in place. Some carburetors may have a fixed main mixture or both a fixed idle mixture and main mixture. NOTE: FOR HIGH ALTITUDE JETTING. followed by the small brass washer and the O ring seal.

This will ensure that the inlet needle will move up and down in a straight line (diag.
PUSH IN UNTIL SEAT RESTS ON BODY SHOULDER IF YOUR CARBURETOR HAS A STEEL SEAT RETAINING RING RE-INTSALL AFTER SEAT INSTALLATION INLET NEEDLE SEATS AT THIS POINT
5/32" (3. Place the inlet needle and spring clip onto the float as shown. 51).969 mm) flat punch. 3. reinstall the inlet needle on to the float and place it into the carburetor (diag.
LONG END OF CLIP Points toward choke end SERIES 7 WALBRO / LMK
53
CLIP
OPEN END OF CLIP
54
POINTS TOWARD THE CHOKE END
55 20
. To prevent binding. Some Tecumseh float style carburetors have a damper spring which is installed as shown in diag.Inlet Needle and Seat
Make sure the seat cavity is clean. position carburetor float side up for assembly. 2. install the seat retainer into the cavity and push it down using the flat punch until it contacts the seat. Position the needle into the fuel inlet and snap the float pin into the tabs on the float bowl. Float height is not adjustable. see adjusting procedure. Press the seat into the cavity using a 5/32" (3. the long. On Series "7" carburetors. slide the hinge pin into the hinge on the float.
LONG END OF CLIP Points toward choke end
CLIP OPEN END OF CLIP THROTTLE END
CHOKE END
52
Float Installation
On Series 7 carburetors. 4. 53). When rebuilding a carburetor with a clip on the needle. On Series 7 carburetors and the Walbro LMK. To set the proper float height on carburetors except Series 7 and Walbro LMK. making sure it is firmly seated (diag. 53). straight end of the clip should face the choke or air filter end of the carburetor as shown (diag. 52). 55. The long end of the spring clip must point towards the choke end of the carburetor. Moisten the seat with oil and insert the seat with the grooved side down and away from the inlet needle. 1.969 mm) FLAT PUNCH SEAT
INSERT THIS FACE FIRST
51
The inlet needle hooks onto the float tab by means of a spring clip.

Firmly push the bulb and retainer into position using a 3/4' (19.Fuel Bowl And Bowl Nut
Whenever a carburetor bowl is removed for service. assemble the carburetor to the engine. a definite fuel flow should result at the pump outlet. Make sure fuel is available in both fuel tanks and the original fuel tank's fuel line is connected to the fuel pump inlet. Make sure the deepest end of the bowl is opposite of the inlet needle. preset the main mixture adjustment screw. lubricate the O ring with a small amount oil. The bowl has a small dimple located in the deepest part.
58
21
. leaving the fuel line from the pump off. If the flow is erratic or intermittent. See Pre-sets and Adjustments in this chapter. Place the pump outlet line in a proper draining receptacle.
VALVE CLOSED ATMOSPHERIC VENT
VALVE OPEN DIAPHRAGM FILTER AIR BLEED
VALVE OPEN FUEL SUPPLY
VALVE CLOSED
PULSE LINE TO CRANKCASE
FLOW DIRECTION á SUCTION FUEL PRESSURE ATMOSPHERIC ê CAUSED FUEL FLOW
ê CRANKCASE PRESSURE á ATMOSPHERIC PRESSURE ACTING ON DAMPING DIAPHRAGM á FUEL FLOW
ê CRANKCASE SUCTION AND FLOW DIRECTION á
ATMOSPHERIC PRESSURE ACTING ON DAMPING DIAPHRAGM
57
Primer Bulb
To install. The parts are designed so they cannot be misassembled without damage (diag.
56
CARBURETOR FITTING
Impulse Fuel Pump
The diaphragms must be installed against the center body with the gaskets against the outside covers.
DETENT
Installing the Float Bowl
Install the float bowl by placing the detent portion opposite of the hinge pin. With the pulse line connected from the engine crankcase to the pump and the engine running.05 mm) deep well socket (diag. 58). the fuel bowl O ring (or gasket on Series "7") and the bowl nut washer must be replaced.
Final Checks
Before reinstalling a newly overhauled carburetor. the idle mixture adjustment screw and the idle speed adjustment screw. For easier installation. start the retainer and bulb into the casting with the retainer tabs pointed out. Use a different fuel tank remotely placed above the carburetor to provide gravity fuel flow to the carburetor inlet to run the engine while testing the pump. The purpose of this dimple is to minimize the chances of the float sticking to the bottom of the bowl caused by stale fuel. 57). To test the unit. the pump needs repair or replacement.

P.P.M. and off to one side on other governor systems. the engine will require disassembly to inspect the governor gear assembly for damage. binding. surging up and down) indicates that the engine is incapable of maintaining a constant R. If the engine runs wide open (faster than normal). using a pliers or fingers.
OPERATION
As the speed of an engine increases. setting slightly may eliminate this condition. The governor rod rotates causing the attached outer governor lever to push the solid link and close the throttle opening.P.P. If the R. stabilizes.P. The shape of the governor weights force the governor spool to lift. cause the governor lever to move the solid link that is connected from the governor lever to the throttle in the carburetor. See Chapter 9 under "Disassembly Procedure" to disassemble the engine.P. The governors function is to maintain a R. drops and is closed as an engine load is removed. See "Service" governor adjustment procedure in this chapter.M.M.P. the governor weights on the governor gear move outward by centrifugal force. wear. When the engine speed decreases. shut the engine off or slow it down immediately. Hunting (engine R. Correct or replace binding or damaged parts. 6. Try to stabilize the engine R.M.M.M. If the engine R. Use the applicable following procedure to diagnose a suspected governor failure.M.M.CHAPTER 4 GOVERNORS AND LINKAGE
GENERAL INFORMATION
Tecumseh 4 cycle engines are equipped with mechanical type governors. the governor or governor adjustment should be checked. If the problem persists after the governor adjustment.
ENGINE OVERSPEEDING
1. the lower centrifugal force allows the governor weights to be pulled in by the governor spring.P. increasing the engine idle R. or improper hookup. check the engine R.P. The governor rod maintains contact with the governor spool due to the governor spring tension. Engine overspeeding must be corrected immediately before serious engine damage occurs.M. Mechanical type governors are driven off the engines camshaft gear. Repair or replace as necessary. setting when engine loads are added or taken away. or wear.P. the engine will require additional checks see Chapter 9 under "Troubleshooting". Repair or replace as necessary. found on microfiche card # 30.see "Service" in this chapter. by holding in one position the solid link between the governor arm and the carburetor throttle. 22
. governor spring. 3.M. 4. does not stabilize. and speed control assembly for breakage or binding. The governor follower arm rests on the center of the governor spool on center force governors. Run the engine.P.M. Follow the governor adjustment procedure and reset the governor . 1). If the engine R.
ENGINE SURGING
1. Check the governor shaft or linkages for binding. with or without an engine load. The governor rod rotates and the solid link moves the throttle to a more open position (diag. The R.P. 2. setting for high and low speed are within specification and a slight surge is experienced. The throttle is opened when the engine R. 2.M. settings are critical.
SPRING
THROTTLE
GOVERNOR SHAFT
WEIGHTS GOVERNOR GEAR
GOVERNOR SPOOL
1
TROUBLESHOOTING
Engine operation problems where the governor is suspected to be the cause may actually be the result of other engine system failures. Remove the governor gear assembly. 5. This chapter includes governor assembly linkage illustrations to aid in governor or speed control assembly. Be ready to shut the engine off if an overspeed problem still exists. 3. linkage. Changes in engine R. If the problem persists. Check the governor spring for adequate tension or damaged condition. Check the condition of the external governor shaft. 4.

55 & OHM.120. 5). Press the shaft in until a part # 670297 (. 3.254-. Start the shaft into the hole with a few taps from a soft faced hammer. Clamp the shaft in a vise and pound gently on the flange with a wooden or plastic mallet to remove the shaft (diag.NEW STYLE
THROTTLE PLATE (TOP VIEW)
ROTATE CLAMP COUNTERCLOCKWISE
OHH SERIES .OHSK 50.508 mm clearance) (diag. On some governor assemblies.010" .. Other governor shafts use an upset to hold the governor spool on.
PUSH LEVER TO WIDE OPEN THROTTLE GOVERNOR CLAMP SCREW
THROTTLE LINK THROTTLE PLATE THROTTLE OPEN (PUSH COUNTERCLOCKWISE) STANDARD LOCATION
GOVERNOR LEVER
Ú
TURN CLIP COUNTERCLOCKWISE ON ALL VERTICAL SHAFT ENGINES EXCEPT VLV & VLXL. 4).OLD STYLE
3
4
GEAR SHIM WASHER SHAFT BOSS
5
670297 (modified)
23
. Grip the original spool in a vise and use a twisting and pulling motion on the flange until the spool is free.0125" / . gear.
Governor Gear or Shaft Replacement. Upset Style Governor Shaft
1.
Ý
GOVERNOR ROD GOVERNOR CLAMP SCREW YOU MUST USE THIS LINK POSITION ROTATE LEVER & ROD COUNTERCLOCKWISE
THROTTLE OPEN (PUSH COUNTERGOVERNOR CLOCKWISE) LEVER GOVERNOR SCREW GOVERNOR ROD GOVERNOR CLAMP
2
OHH SERIES .
GOVERNOR GEAR AND SHAFT SERVICE
After the cylinder cover is removed from the engine. loosen the screw holding the governor lever to the governor shaft clamp.020" / . the retaining ring must be removed to allow the spool or gear to slide off the shaft. 2. the governor shaft will have to be removed. To install a new shaft. CLOCKWISE ON ALL HORIZONTAL SHAFT ENGINES EXCEPT OHH. Hold the lever and clamp in this position while tightening the screw (diag. NOTE: DO NOT TWIST THE SHAFT WHEN REMOVING. If the gear requires replacement.SERVICE
GOVERNOR ADJUSTMENT
With the engine stopped. Rotate the governor clamp counterclockwise on all overhead valve engines covered in this manual. first assemble the gear and washer on the shaft. the governor spool. THE SHAFT BOSS MAY BECOME ENLARGED AND THE PRESS FIT WILL NOT SECURE THE NEW GOVERNOR SHAFT. 4.3175 mm) shim just becomes snug (. Place the flange in a press with a solid piece supporting the area below the shaft boss. or governor shaft can be removed. OHSK 110. 2). Push the governor lever to move the carburetor throttle plate to the wide open position.

25
. The following pages show common linkage hookup arrangements.M. place the equipment control to the "fast" position. or a vertical or horizontal control mounted on the side of the engine.'s should also be checked. and hold the lever in this position while tightening the bowden wire clamp. the hole in the choke actuating lever. To align the control bracket. The ignition ground out terminal.Speed Controls And Linkage
Many different types of speed controls and linkage are used for O. When the engine is running. tighten the two screws on the control panel. 3.M. The solid link is always connected from the outermost hole in the governor lever to the throttle in the carburetor. the governor controls both the idle and the high engine speed. 12
HIGH SPEED STOP
OHH REMOTE SPEED CONTROL
The engine and equipment control must be adjusted to allow the engine control lever to touch the high speed stop when the equipment control is set in the "highspeed" or "fast" position.P. 4. 2. 1. 3. With the components aligned. Use a Vibra-Tach or other tachometer to set the non-governed idle speed (600 RPM lower than the governed idle speed) by pushing the bottom of the governor lever away from the control bracket so the throttle lever contacts the idle speed screw and hold the lever in this position. 1. 12). Use the following procedure to set the engine speeds (diag. Vertical shaft engines may use an adjustable intake pipe mounted speed control bracket located above the carburetor. Check to find the correct engine speeds found on microfiche card # 30 or using the Computer Parts Lookup System. Loosen the two screws on the top of the panel. idle R. move the engine control lever to contact the high speed stop. In order for the governor to respond properly to a crankshaft load at engine idle. The governor spring is connected between the speed control lever and the governor lever. Loosen the bowden wire clamp. Turn the idle speed screw clockwise to increase or counterclockwise to decrease engine idle speed. Whenever the carburetor or the governor linkage is removed or replaced.P. Use microfiche card #30 or contact a local Tecumseh dealer for the correct R. 2.M. adjustment screws may be located on the speed control bracket. The adjustable speed control bracket which is mounted on the intake pipe must be aligned properly when installing.P. Move the control lever to full wide open throttle position and install a wire or aligning pin through the hole in the top of the panel.M. Place the control knob in the lowest engine speed position.E.M. and the hole in the choke (diag. Allow the governor to control the throttle. This assures the correct placement during reassembly. Slide the control knob to the high speed position and bend the tab as shown to achieve the specified governed high engine speed. 14 & 16). NOTE: RPM SETTINGS CAN ALSO BE FOUND ON THE COMPUTERIZED PARTS LOOK UP SYSTEMS. settings for the engine model and specification. the engine R. the idle speed screw on the top of the carburetor must be set 600 RPM lower than the governed idle speed. Use a Vibra-Tach or other tachometer and bend the tab as shown to achieve the specified governed idle speed.P. Start and allow the engine to run ( 3-5 minutes) before beginning adjustments.
13
OHH GOVERNED IDLE SPEED CONTROL
This control is adjusted by bending the tabs on the control bracket to achieve the correct idle speed and high speed. use the following steps. and high speed R. applications. Linkage attachment points are best recorded or marked prior to disassembly.

Place the other washer with the large I. lbs. (2 Nm).HIGH SPEED ADJUST
GOVERNED IDLE ADJUST
OVM / OVXL GOVERNOR OVERRIDE
22
OHV11 . The smaller side of the bushing goes towards the lever and fits inside of the lever and the washer. thus allowing the engine to be stopped at either the stop in the control or the remote grounding switch. Discard the detent bearing plate and in its place install the washer with the smaller I. bushing and washers to ensure that everything is aligned properly and torque the lock nut to 20 in. wave washer. Check the alignment of the lever. Remove the air cleaner cover and air cleaner element to gain easier access to the speed control lock nut that holds the control levers together. This engine speed control is set up with the "stop in the control". It will now be necessary to run a grounding wire to a remote grounding switch in order to stop the engine. Reinstall the blade and screw. control lever. Install the lock nut. then the bushing. A remote grounding switch can be added to the engine at this terminal as well. If a remote stop is desired remove and discard the short green wire that runs from the speed control grounding terminal (to the remote grommet stop blade). 27
.525 mm) locknut. bushing. Install the lever over the post making sure that the end of the lever is in the slot of the control. from the parts bag next to lever. from the new parts bag. Remove the 3/8" (9.D.17 SPEED CONTROL
23
SPEED CONTROL BRACKET
DETENT BEARING PLATE
CONDUIT CLIP
BUSHING LOCK NUT SCREW CONTROL KNOB
GROUNDING TERMINAL WAVE WASHER ADDITION BOWDEN WIRE BRACKET
CONTROL LEVER
WASHER
NOTE: THIS CONTROL IS STANDARD ON SERVICE ENGINES AND IS OPTIONAL TO CUSTOMERS
24
CONVERSION TO REMOTE CONTROL
Remove the manual control knob by squeezing together with a pliers or prying with a screw driver. The control lever should move freely. and the detent bearing plate. Reassembly of REMOTE control.D. Discard the wave washer.

M.P. Use tool part # 670326 to adjust the high speed engine R. Throttle plate alignment on all models with speed controls mounted on intake manifold. In this position. OHV 11 -17 engines use nylon bushings on the throttle and choke linkage hook-up points to extend the life of the linkage and to enhance the stability of the governor system.M.M. and tighten the cable housing clamp. and the option of an ignition remote stop terminal block.
IDLE ADJUSTING SCREW
HIGH SPEED ADJUSTMENT TAB THROTTLE LINK HOOKUP ALIGNMENT HOLE
OHV 11-17 HORIZONTAL SPEED CONTROL
This speed control is adjusted to the equipment throttle control by aligning the slot in the speed control lever with the alignment hole on the mounting bracket. the gap of . In this position.070 (1. NOTE: Assure that the throttle cable has full travel from wide open throttle to full choke. hook the bowden cable end in the control as shown.M. and tighten the cable housing clamp.P.1.778 mm) should exist at the gap location as illustrated. place the equipment throttle control to the wide open position. This adjusts choke in control as well (diag.778 mm) BEND TAB TO ADJUST
OHV 11 .P..040 .070" (1. place the equipment throttle control to the wide open position.P. This will assure that the carburetor will go into full choke when the control is placed in the start position. 28
TOOL #670326
Þ
OVM..17 HORIZONTAL CONTROL
26
LINKAGE BUSHING
27
. Place the slotted end of the tool onto the adjustment tab and bend the tab to the left (toward the spark plug end) to increase engine R.This remote speed control may have governed idle.1.M.M.02 .040" . The speed control is adjusted to the equipment throttle control by aligning the slot in the speed control lever with the alignment hole on the mounting bracket.P. OVXL. The idle speed is adjusted by turning the idle speed screw clockwise to increase engine R. the gap of .P.040 .778 mm) should exist at the gap location as illustrated. Hard starting could result if the cable is not properly adjusted to allow for full choke.070" (1.070") (1.M..778 mm) GAP LOCATION CHOKE ADJUSTING TAB CONTROL LEVER HIGH SPEED PIN POSITION
OHV VERTICAL CONTROL
25
CHOKE HOOKUP IDLE SPEED SCREW
CHOKE LEVER AIR GAP (. Place the slotted end of the tool onto the adjustment tab and bend the tab to the left (away from the control) to increase engine R.. This will assure that the carburetor will go into full choke when the control is placed in the start position.02 . Make sure they are in good condition and in place (diag. 12 on page 25). hook the bowden cable end in the control as shown.P.M.02 . 27). Use tool part # 670326 to adjust the high speed engine R. a choke override. and counterclockwise to decrease R.P. Place a pin through the two holes.02 . and counterclockwise to decrease R.1. OHV VERTICAL SPEED CONTROL
DECREASE
INCREASE
Þ
HIGH SPEED ADJUSTING LEVER BEND TO ADJUST HIGH SPEED
.1. Place a pin through the two holes. The idle speed is adjusted by turning the idle speed screw clockwise to increase engine R.040" .

Visually inspect the starter dog(s). All recoil starters turn the engine over by engaging a dog(s) into the starter cup attached to the engine flywheel. repair.
29
. the recoil spring turns the starter pulley in the opposite direction to retract the starter rope. the starter pulley rotates on the center pin. and the starter pulley for wear or breakage. springs. Use one of the following procedures that apply to the application to disassemble.CHAPTER 5 RECOIL STARTERS
GENERAL INFORMATION
Recoil starters used on vertical shaft Tecumseh engines are top mount horizontal pull style. and assemble the starter. Always consult the Tecumseh Master Parts Manual for the correct replacement parts. retainer. The retainer ears act as a ramp to fully extend the starter dog(s). The starter dog(s) is pinned or pocketed in the pulley hub and extend outward when the pulley rotation forces the starter dog(s) to contact the ears on the retainer. When the starter handle is released.
COMPONENTS
ROPE HANDLE STARTER HOUSING HANDLE HOUSING
PULLEY AND REWIND SPRING ASSY. STARTER DOG DOG SPRING WASHER RETAINER BRAKE SPRING WASHER SPRING PIN DOG SPRING RETAINER BRAKE SPRING
SPRING & KEEPER
PULLEY
1
DOG BRAKE WASHER CAM DOG CENTER 2 SCREW
SERVICE
Starter related problems will require the starter to be removed from the engine to diagnose the cause. The starter dog spring(s) returns the starter dog(s) to the disengaged position. washers. and size required. The fully extended starter dog(s) locks in contact with notches in the starter cup. When the engine fires and the rotational speed of the starter cup exceeds the starter pulley. Horizontal shaft engines use recoil starters which can be mounted to pull either vertically or horizontally. the starter dog(s) disengages from the starter cup. All starters are spring loaded to retract the dog(s) when the engine speed exceeds the turning speed of the starter.
ROPE SERVICE
Rope replacement should be done using the correct part number replacement rope or braided rope of the correct diameter and length. length. Use the following rope chart to convert a numbered rope to a fractional diameter for bulk rope use. starter cup. Consult the Tecumseh Master Parts Manual to obtain the correct part number. rope. The rope ends should be cauterized by burning with a match and wiping the rope end with a cloth while hot.
OPERATION
As the starter rope is pulled.

STARTER DOG DOG SPRING WASHER RETAINER
LEFT-HAND KNOT
BRAKE SPRING WASHER SPRING PIN
4
5
30
. AND EXTINGUISH COMPLETELY BEFORE DISCARDING. Install the starter handle and tie a left hand knot to secure the handle.35 mm) punch for stamped steel] roll pin punch to drive out the center pin. OHSK. 2. All components in need of service should be replaced. # 4 1/2 rope = # 5 rope # 6 rope = = 9/64" diameter (3. OVM. PULLEY BOSSES HOLD THE REWIND SPRING AND COVER. Slide the rope retainer into the proper position and insert the staple using a pliers. Remove the staple and old retainer. 4). 6. Move the punch around while driving the pin to help keep the pin straight. 3. After removing the rewind assembly from the engine blower housing. Remove the brake spring. Remove the starter handle if the retainer is a complete circle design. The stamped steel center pin is driven out from the outside.
ONE PIECE ROPE RETAINER STAPLE
3
STYLIZED REWIND STARTER (OHH. 5. Note: The starter dogs face out on the stamped steel starter and the dogs face in on the stylized rewind starter.4 mm) deep well socket under the retainer. AND CAN BE EASILY DISLODGED DURING HANDLING. and STAMPED STEEL STARTER Disassembly Procedure
1. Remove the starter handle and carefully allow the rope to unwind into the starter housing (diag. washers. OHM. 4). OHV).969 mm) 3/16" diameter (4. OVRM. OVXL. Place a 1" (25. Remove the decal or plastic disc in the center of the rewind. CAUTION: THIS REWIND SPRING IS NOT SECURED IN A CANISTER.937 mm) or a [1/4" (6. Use a 5/16" (7. supported on the socket.572 mm) 5/32" diameter (3.CAUTION: HANDLE MATCHES SAFELY TO AVOID BURNS. 2. 4. the punch tip must be angled inside the center hole. 3. release the tension on the rewind spring.762mm)
ROPE RETAINER REPLACEMENT
1. and pulley assembly (diag. Set the rewind on a bench.
HANDLE
ROPE STARTER HOUSING
PULLEY AND REWIND SPRING ASSY. retainer.

tying a temporary knot in the exposed rope. (diag.
RETAINER WEDGE
STARTER HOUSING
STARTER PULLEY SPRING & COVER
DOG SPRING STARTER DOG
DOG RETAINER
8 31
. and either untying the knot in handle or prying out the staple. Discard the old plastic washer. Place the rewind on a flat surface and drive the new center pin in until it is within 1/8" (3.175 mm) of the top of the starter. the tabs on the retainer must be positioned so that they will force the starter dogs to engage the starter cup.
DOG SPRING WASHER RETAINER
STARTER DOG BRAKE SPRING
WASHER SPRING PIN
6
STARTER HOUSING HANDLE ROPE PULLEY AND REWIND SPRING ASSY. 3. Install a new recoil spring if necessary by pushing the new spring out of the holder into the pulley cavity while aligning the outside spring hook into the deep notch in the pulley. Push the spring cover in until seated. Reattach the starter handle to the rope using a left-hand knot. Untie the temporary knot and slowly allow the rope to fully retract into the starter housing and the recoil spring to fully unwind. Pull enough rope through to tie a temporary knot in the rope. Place the two new plastic washers between the center leg of the starter and the retainer. 5. The retainer will bend and the starter dogs will not engage the starter cup. Reverse the disassembly procedure. On the stamped steel starter the center pin should be driven in until it contacts the shoulder in the starter housing.
STARTER HOUSING HANDLE HANDLE INSERT ROPE
PULLEY AND REWIND SPRING ASSY. 6 & 7) 2. remove the starter handle by first pulling a length of rope out using the handle.Assembly Procedure
1. The starter dogs with the dog springs must snap back to the center of the pulley (disengaged position). After removing the rewind assembly from the engine blower housing. Remove the decal from the center of the starter housing. Always replace the center spring pin with a new one upon reassembly. NOTE: DO NOT DRIVE THE CENTER PIN IN TOO FAR. 4. 2. 3. Replacing rope wind the starter pulley counterclockwise four or five turns to pre-load the recoil spring and thread the rope through the starter housing eyelet. DOG SPRING STARTER DOG WASHER RETAINER
LEFT-HAND KNOT
BRAKE SPRING WASHER SPRING PIN
7
STYLIZED REWIND STARTER WITH PLASTIC RETAINER Disassembly Procedure
1. New plastic washers are provided with a new center spring pin. Untie the temporary knot and allow the rope to recoil. When the rope is pulled.

Turn the spring and keeper assembly to remove the pulley. see Step 8. 7. Untie the temporary knot and allow the rope to recoil. Lift the pulley out of the starter housing. Turn the starter over and snap the locking tab between the retainer legs. Replace all worn or damaged parts. Pinch the legs of the retainer together and pull on the head of the retainer to remove it from the housing. Wind the starter pulley counterclockwise four or five turns to pre-load the recoil spring and thread the rope through the starter housing eyelet. 7. Push the retainer in until the leg prongs pop out of the center shaft. 3.
RETAINING WEDGE (STEEL CLIP . 5. 5.NEW STYLE)
STARTER HOUSING
Assembly
1. 6. Untie the knot in the rope and slowly release the spring tension. Repair or replace as necessary. 2. retainer (cam dog on snow proof type). 4. Apply a small amount of lithium grease to the inner bore of the center shaft. NOTE: Refer to Service Bulletin 122 for metal locking tab.
STARTER PULLEY SPRING & COVER
DOG SPRING STARTER DOG
DOG RETAINER
9
STARTER HOUSING REWIND SPRING AND KEEPER ASSY. Push the spring cover in until seated. If replacing the starter rope. 8. Pinch the two legs of the plastic retainer together and start into the center shaft hole. Rotate the retainer so the two tabs on the bottom of the part fit between the dog and pulley hub (left side of the dog). Use a small Phillips screwdriver or similar tool to pry the retainer legs apart and lift out the retaining wedge. 3. 6. replace the top decal. and brake spring (diag. 2. 32
HANDLE
HANDLE INSERT
PULLEY
LEFT-HAND KNOT
CAM DOG WASHER
DOG SPRING STARTER DOG DOG RETAINER RETAINER SCREW BRAKE SPRING SPRING PIN
"STAMPED STEEL WITH ROLL PIN"
10
. ROPE
KEEPER SPRING STYLE STARTERS Disassembly Procedure
1.4. Remove the pulley assembly from the recoil housing. starter dog(s) and dog spring(s). Install a new recoil spring if necessary by pushing the new spring out of the holder into the pulley cavity while aligning the outside spring hook into the deep notch in the pulley. Pull enough rope through to tie a temporary knot in the rope. Reattach the starter handle to the rope using a left-hand knot. 10). Replace or check that both starter dogs are in the pulley pockets and that the dog springs are hooked on the outer surface of the dog. Remove the center screw.

5 Nm) torque. 3.Apply blue Loctite to the center screw and torque to 70 in pounds (8 Nm). metal washer. 2. Replace the starter rope if removed by inserting one end through the hole in the side of the pulley and tying a left hand knot near the rope end. 4. Remove the nut (using a 10 mm socket) and washers from the center leg of the recoil housing. Remove the starter pulley. thread the rope through the starter housing hole.Stylized Starter (OHV 13. HOUSING BOSSES HOLD THE REWIND SPRING. and place a temporary knot in the rope leaving at least one foot of rope length. NOTE: Type II . tying a temporary knot in the exposed rope. 5. lock washer. hook the end of the dog spring into the hole in the retainer. Insert the starter dogs on the pulley pegs with the flat side away from the pulley. AND THE SPRING CAN BE EASILY DISLODGED DURING HANDLING.5 -17)
1. Remove the starter dog retainer. 34
STARTER DOG BRAKE SPRING LOCKWASHER STARTER DOG RETAINER CENTER SCREW
STARTER HOUSING
SPRING AND KEEPER
PULLEY
STARTER DOG RETAINER SPRING WASHER
TYPE II
15
. place the brake spring and starter dog spring on the pulley. 3. Tighten the hex nut to 40 inch pounds (4. align the end of recoil spring and the notch in the pulley and push down until seated. Slide the starter handle on the end of the rope and secure using a left hand knot. 2. add the nylon washer. Remove the temporary knot and allow the rope to retract. Untie the temporary knot and slowly allow the rope to fully retract into the starter housing and the recoil spring to fully unwind.
LEFT-HAND KNOT
STARTER HOUSING
REWIND SPRING
PULLEY BRAKE SPRING STARTER DOGS
STARTER DOG SPRING STARTER DOG RETAINER WASHER LOCKWASHER 6mm METRIC NUT
TYPE I
14
Assembly
1. and hex nut. press down and turn 1/2 a turn clockwise to line up the notches to the starter dogs. Place the starter dog retainer on the center leg. 6. 4. Place the pulley on the housing center leg. 5. Remove the starter handle by first pulling a length of rope out using the handle. starter dog spring. brake spring. CAUTION: THE REWIND SPRING IS NOT SECURED IN PLACE. Pull the knot into the squared area and wind the rope counterclockwise (viewed from the pulley bottom) on the starter pulley. Slowly unwind the dog spring by allowing the starter dog retainer to rotate. The starter dogs must be free to retract into the pulley pocket. 6. Remove the starter rope from the pulley if necessary. and untying the knot in the handle. Wind the pulley counterclockwise 4-5 turns. and starter dogs.

rectifiers or diodes. The power source used to provide the energy to turn an electric starter motor on Tecumseh engines is either 120 volt A. the pinion rotates along with the armature shaft to crank the engine.CHAPTER 6 ELECTRICAL SYSTEMS
GENERAL INFORMATION
The electrical system consists of three main elements: a battery. The starting circuit includes the battery. a current is induced in the alternator coil. The battery is part of both the starting and charging circuit. If a battery has a shorted cell. overcharging can result. The engine needs to be running to produce an electric current flow. The battery should be checked before going into any extensive starter or charging system checks. All engines that have a charging system will use a combination of some or all of these features. The armature magnetism repels the magnetism produced by the permanent field magnets of the electric starter. battery cables. ignition switch.
ROTATION OF FLYWHEEL
2 35
. regulator. the starter switch closes the starting circuit.C. The greater momentum of the flywheel throws the starter pinion gear out of mesh and forces the starter pinion back to the disengaged position. When a conductor (alternating coils) cuts the magnetic field generated by the magnets in the flywheel. moving the drive pinion laterally on the splined armature shaft.
LOCK NUT BOLT BRUSHES BRUSH SPRINGS BRUSH CARD HOUSING END CAP WASHER NUTS
ARMATURE SPRING RETAINER RETAINER GEAR SPRING DUST COVER THRUST WASHER END CAP ENGAGING NUT
1
CHARGING CIRCUIT
The charging system works independently of any manual controls. safety switches. The permanent magnets in the flywheel have a magnetic field in which the lines of magnetic force run from the North Pole to the South Pole. starter circuit utilizes a 120 volt power source instead of a battery. and an electric starter motor. If a cell has an open or high resistance connection. the direction of the magnetic field changes or alternates. The armature and pinion remain positively engaged until the engine fires and the flywheel rotates faster than the armature.C. the electric starter operation will be affected. The alternating coils are wound in different directions to allow current to flow as an A. current or 12 volt D. As the flywheel rotates and the position of the magnets change. When the drive pinion contacts the stop at the end of the armature shaft. starter or ignition switch. and the regulator or rectifier may appear to be at fault. A strong magnetic force is produced by the electrical current running through the armature windings. starter solenoid. a starting circuit. The repelling magnetic forces cause the armature to rotate. and a charging circuit. A 120 volt A. 2). and a battery. After the switch is released. A small anti-drift spring holds the pinion in the disengaged position (diag. waveform (diag.
OPERATION STARTING CIRCUIT AND ELECTRIC STARTERS
After all of the safety interlock switches have been activated.C.C. The charging system consists of alternator charge coils. 1). The 12 volt battery models require a charging system to maintain proper battery charge. the starting circuit is opened and the armature coasts to a stop. meshing the starter pinion gear with the flywheel ring gear. flywheel magnets.

In certain situations it is necessary to make use of the entire A.VOLTAGE
A. It does not allow the negative portion through. signal.C.C. it is necessary to convert alternating current (A. 4).
+ VOLTAGE HALF WAVE RECTIFIER (SINGLE DIODE) + VOLTAGE
A.C.C.VOLTAGE .C. INPUT . 36
. 5). OUTPUT
4
Full Wave Rectifier Bridge Rectifier
The full wave rectifier makes use of the entire A.C. securely fastened and free of foreign material (such as rust and corrosion) at the connection points. To accomplish this. This is accomplished by using a diode or rectifier (diag. Consult the original equipment manufacturers service manual for battery size.
ANODE
CATHODE
BAND OR OTHER MARKING INDICATES CATHODE END
3
Current flows through a diode when the anode is more positive than the cathode. converting it to D.
+ VOLTAGE
FULL WAVE RECTIFIER (BRIDGE RECTIFIER)
COMPONENTS BATTERY
The batteries used in conjunction with Tecumseh engines are 12 volt lead acid or maintenance free style.C. CONDITION: All wiring must be fully insulated between connection points.C. signal through. INPUT
+ VOLTAGE (D. multiple diodes in a bridge configuration are used to produce FULL WAVE RECTIFICATION (diag. signal and is known as HALF WAVE RECTIFICATION (diag.)
+ VOLTAGE
D. A single diode makes use of only one half of the A. This is acceptable in certain applications. Remember to check the insulation on the wire. All it takes is a pin hole for leakage to "ground out" on the engine or frame.C.). This is especially important in the use of batteries where much of the potential may be lost due to loose connections or corrosion.
Half Wave Rectifier Single Diode
The single diode allows only the positive half of the A. signal. The chemical energy produced by the dissimilar metals of the battery plates provides a electrical potential that is used to power the electric starter or unit accessories.CONVERTING ALTERNATING CURRENT TO DIRECT CURRENT
In order to charge a battery. capacities.) to direct current (D.C. This is of special concern when moisture or water is present.C. and testing procedure. INPUT
A.
.VOLTAGE
5
WIRING
The wires used in Tecumseh electrical systems are copper stranded with an insulated coating around the copper strands.C.C. OUTPUT . 3).VOLTAGE
D. The cathode end of the diode should point toward the battery when diode is used between a charging system and a battery.

The magneto circuit wiring (ground circuit) must be rated at #18 or lower gauge number.This combines a regulator with a rectifier. When a magnet is moved past the coils. The charging circuit wiring must be rated at #16 or lower gauge number (20 amp system requires #14 or lower gauge number). 2. 2. 6).An alternator consists of coils of wire wound around a metal lamination stack. 1.
THE LARGER THE NUMBER THE SMALLER THE WIRE
# 18
#6
6
Tecumseh Products Company's standard wiring color codes effective August. Cracked insulation or broken wires. .Leads Alternator Ground Leads. 3. 3. the greater the number of coils. the greater the output of the alternator.
ELECTRICAL TERMS
ALTERNATOR . WIRE CODES CHANGED ACCORDING TO MODEL AND SPECIFICATION NUMBERS. 37
.C. In general. be sure to perform the more basic checks first. Silver. A wire "grounding out" in the system.A conductor is a material that allows an electric current to pass through it.Charging a battery requires that the alternating current produced by the alternator be changed to direct current. As the gauge number of the wire increases. such as: 1. REGULATOR/RECTIFIERS . 1992 are as follows: Code Yellow Red Brown Black Orange Product Alternator A.C. Corroded or loose terminals or connections.
BASIC CHECKS
Before going into extensive checks. INSULATORS . Defective switch. 4. a current is induced in the coils. CONDUCTORS . but some are better conductors than others. Operator presence system functioning properly. rubber.An insulator is a material that will not allow an electric current to pass through it. copper and gold are some of the better known conductors. Leads Alternator D.C. IF THE TRACTOR IS "CUTTING OUT" OR WILL NOT START. All metals are conductors of electricity. or wrong connections. 6. This is accomplished by using a diode or rectifier. THIS IS AN AREA THAT SHOULD BE CHECKED OUT. 5.WIRE GAUGE: The proper thickness of wire is necessary in all electrical circuits. The starter circuit wiring must be rated at #6 or lower gauge number. + Leads Alternator D. Battery defective or not charged. Some of the more common materials that are insulators are glass. ceramics and porcelain. the wire diameter decreases in size (diag.* *NOTE: ALL LAWN AND GARDEN TRACTORS BUILT AFTER JULY OF 1987 ARE REQUIRED TO HAVE AN OPERATOR PRESENCE SYSTEM AND MANY CAME EQUIPPED WITH SUCH A SYSTEM PRIOR TO THIS DATE. RECTIFIERS and DIODES . plastic. Battery Ground Leads 12 Volt Starter B + Leads Ignition Shut-Off Leads
Dark Green -
NOTE: PRIOR TO AUGUST 1992. The regulator prevents overcharging of the battery and the rectifier changes the alternating current to direct current. Wire diameter is measured in increments of gauge numbers.

replace if no continuity exists or if continuity exists reversing test leads Check fuses. or lights for shorts
39
. or ammeter for breaks.
Check diodes. shorts
Alternator coil failure. replace coil assy. replace as necessary Check switches. wiring.TROUBLESHOOTING ELECTRICAL CHARGING CIRCUIT FLOW CHART
Identify the charging system used by model and specification number or visually checking the electrical plug Consult the Mechanic's Handbook or Electrical Troubleshooting booklet for test procedure for the charging system used Test for either AC or DC voltage as directed at the proper engine RPM
NO
Is the voltage greater than or equal to the minimum value?
YES
NO
Is AC voltage before diode or YES rectifier greater than the minimum value?
Check wiring. switches.

however. Connect a voltmeter across the battery.C. volt scale. OUTPUT LEAD (RED) ELECTRIC STARTER LEAD (ORG)
7
.20 D.C. VOLTAGE. The SCR senses this and there will be no D. a mechanical binding may be the cause. there should be an increase in the voltage reading. the engine will require to be disassembled to find the mechanical failure. 3. 7. the problem is an internal failure.C. Make sure the battery meets the minimum battery voltage requirements found in the original equipment manufacturer's service manual.C. check the engine valve clearance per the specification table in Chapter 10. With the engine running. Check wiring. Set the voltmeter to the 0 . See "Service" in this chapter. 2. 4. fuses. check cannot be made. Without the battery in the circuit this turn on voltage is not present. Each charging system has its own testing procedure. 5. Start the engine. If the preceding steps fail to correct the problem. output from the regulator / rectifier. ELECTRIC SHOCK CAN KILL.C. Check the power source using an electrical tester and following the tester's recommended procedure. the electric starter should be replaced or disassembled and checked. connections. Valve clearance not within the listed specifications will require resetting the rocker arms to obtain the proper clearance. Repair or replace as necessary. Remove all equipment loads from the engine.M. Take off all drive belts.) using a voltmeter.C. CAUTION: FOLLOW ALL SAFETY PRECAUTIONS WHEN TESTING FOR A.
CHARGING CIRCUIT
The following pages will show wiring diagrams of several Tecumseh charging systems. If the valve clearance is within the specifications. See Chapter 9 for "Disassembly Procedure" (diag. Check the electric starter terminal for the required voltage (12v D. In some cases an open circuit D. the alternator is defective and should be replaced. If the engine doesnt turn over. The charging system used on the engine is best identified by obtaining the engine model number and the specification number on the engine. or 120v A. Checking at one of the speeds is sufficient. or solenoid for continuity using a ohmmeter or a continuity light. To make many of the tests it is necessary to run the engine and measure alternator output with a voltmeter. 7). starters labeled CSA must only be replaced. 6. and couplers to isolate the engine from the equipment it is powering. A SCR (Silicon Controlled Rectifier) is located in the circuit which requires a minimum turn on voltage to allow it to conduct. If the engine binds only on the compression stroke. Test the charging system using the applicable procedure found on the following pages.TESTING PROCEDURE STARTING CIRCUIT
1.P. ignition or starter switch. Consult a Tecumseh dealer or a parts manual to identify the charging system.s. 120 volt starters labeled UL Listed/CSA Approved can be serviced. If there is no change in the voltage reading. it is not necessary to take readings at all the listed R. Try to turn the engine over using the recoil assembly if equipped.C. When making voltage tests with the engine running. If no problem is discovered. See Chapter 9 under "Disassembly Procedure". safety switches.
(+) POSITIVE LEAD
350 Milliamp Charging System
CHECKING THE SYSTEM: The battery must be in the circuit to perform the test properly. chains. The voltmeter should read the battery voltage. the camshaft (compression release failure) may require replacement. If the engine turns over freely. Check for proper lubrication (oil level and viscosity) and check for electric starter gear and flywheel ring gear interference. 40
(-) ENGINE GROUND MAGNETO GROUND (GR) BATTERY GROUND (BL) BLACK RED D.

18 watt bulb.C.
TWO DIODES RED
D.
10 41
. checking the D.8.C.0 Volts A.C.
YELLOW GREEN IGNITION STOP YELLOW YELLOW
9
2. . voltmeter as shown (diag. 22 Volts A.M. disconnect the plug from the rest of the lighting system.10.C. Connect another wire lead to the other terminal of the bulb and run to a good ground on the engine. THE A.M. Lighting Alternator
CHECKING THE SYSTEM: To check the system.C. D.C.C.18 Watt A.10.)
A. If minimum values are noted.C. R.C.C.C.M.M.C. 26 Volts A.C. 3600 R. 2500 3000 3600 Volts A. wiring or switches.C.C.
NOTE: These minimum numbers should be obtained by your meter and will often be higher.C. shorted wires and burned out headlight and/ or stop tail light. .M. is good check each diode it services as requested see parts list. OUTPUT LEADS ARE BLACK AND RED.11.P. 3600 .10.11. outputs both sides. 3600 R.C. the alternator is defective.C.C. 18 Volts A. 3000 R. .C. Start the engine and test the circuit using the A.C. .M. If A. minimum values should read: 2500 R.9.5 Volts A.M.5 Volts A.P. output. the alternator is okay.M. R.0 Volts D.5 Volts A. lead to ground at each yellow wire (diag. NOTE: ON OLDER POINT IGNITION SYSTEMS. 3300 .P. Connect a wire lead from the single pin connector coming out of the engine to one terminal of a No. check the A. D.C.M. See Chapter 9 for "Disassembly Procedure". A. valve (+) or (-) check A. the alternator is okay.8.5 Volts A.C.C. neg and D. check for inoperative switch.5 Volts D.8.C.0 Volts A.C.C.P.
D.C.C. the alternator is defective.6. POSITIVE OUTPUT LEAD (RED D.5 Amp D.P.P. minimum A.
#4414 BULB
ENGINE
YELLOW
8
3 AMP
Before making any exterior tests.P. NEGATIVE OUTPUT LEAD (BROWN D. 35 Watt Lighting
To check this system follow the meter hook ups at the right. With the engine running.C.C.P. 9). .9.C. If less than the minimum values. 3300 R. With engine running. positive first. It the above minimum readings are noted.5 Volts D.0 Volts A. 3000 R. if less than the above readings. voltage across the bulb should be: 2000 R. .)
D. 4414.C.C. If output is below standard listed pull back protective coating in front of the diode and check A.5 Volts D. To check out the alternator.C. 3000 . . Volts 2500 .
D.. See Chapter 9 for "Disassembly Procedure".C. 8). Check for defective lights.P.

voltmeter. disconnect at plug (spade terminal) and cut the wire on the opposite end of the diode at the solderless (crimped) connector.C. etc.P.C.C. replace with a six (6) AMP fuse.) is used to provide a trickle charge for the battery. 3300 R. -10. Place the solderless connector from the new diode onto the exposed 1/4" (6.35 mm) wire and crimp the connector with a standard electricians pliers. but the output readings will be the same.C.C. To replace the diode. replace the diode. proceed to make an A. If no reading or less than the above reading.C.
Þ
12 13
.5 Volts D. .P.M. output.P. If low or no voltage is experienced.C.M. Ground the other probe to the engine (diag.
11
FUSE HOLDER
IF BULB DOES NOT LIGHT OR LIGHTS WHEN POLARITY REVERSED. 11).0 Volts A.P.P. With the engine running minimum values should read: 2500 R.C.C.M. If the alternator puts out the minimum A.35 mm) of insulation from the cut end of the wire and twist the strands together. 42
SPADE CONNECTOR SOLDERLESS CONNECTOR
RED DIODE GREEN
D. 3600 R. .M. 3000 R.P. output check by pulling back the protective coating from the wire on the alternator side of the diode.8. Check for bad battery. separate the connectors at the engine.3 AMP DC ALTERNATOR SYSTEM DIODE IN HARNESS SLEEVE
This system has a diode included in the red wire which converts the alternating current (A. 3600 R. wiring.26. Place the probe (+) in the red wire lead connector.C. NOTE: DO NOT USE ACID CORE SOLDER. .) to direct current. voltage before the diode using an A.C.C. DISCARD DIODE.USE A HEAT SINK. To check D. . voltage. replace the alternator. New heat shrink tubing can be installed by slipping over the wires and heating with a hot air gun. ammeter.M.5 Volts D.P.24.9.0 Volts A.C. 3300 R.0 Volts A. the system is okay.0 Volts A. If this is not available. 3000 R. . -11. BE CAREFUL NOT TO APPLY HEAT DIRECTLY TO THE DIODE . CHECKING THE SYSTEM: Remove the fuse from fuse holder and check the fuse to make certain it is good.18. If faulty.22.M. The leads from the alternator and the type of connector may vary. 12).C.5 Volts D.0 Volts D. If one of these minimum readings are noted.P. tape the diode and connections with electrical tape.M. With the engine running minimum values should read: 2500 R. The direct current (D. Remove 1/4" (6.M. Test the A.C. Reconnect plug end (or spade connector (diag.C. .

Test the diode in the harness by using a continuity test (diag. system used to charge a battery with a 5 Amp A. VOLTMETER
CAUTION: BLOWER HOUSING MUST BE INSTALLED WHEN RUNNING ENGINE
14
3 Amp D. system used for lighting.C. 12).C. Replace the diode if continuity exists after reversing tester leads or no continuity is found. 3600 R. Reinstall the blower housing. OUTPUT TEST. 14).M. See Chapter 9 for "Disassembly Procedure".0 Volts A. charging system to power an electric clutch without the use of a battery.
INSERT PROBES INTO CONNECTOR SLOTS. Test the charging system using the applicable " Checking the System " procedure listed in this section.P.C.M.26.C. the blower housing must be removed.C. If a known good battery fails to maintain a charge.C.19.C.C.M.C. 3300 R. voltage test. Located in the red wire of the harness is a diode which converts the alternating current to direct current for charging the battery.C. . If the minimum values are noted.C.C.P. If less than above readings. voltage check cannot be made with this system. ALTERNATOR SYSTEM REGULATOR-RECTIFIER UNDER BLOWER HOUSING
CHECKING THE SYSTEM: An open circuit D.
RED LEAD DIODE 3 AMP D.0 Volts A.C.C.P.0 Volts A. the alternator is ok and the regulator-rectifier is defective. the alternator is defective. CAUTION: AT NO TIME SHOULD THE ENGINE BE STARTED WITH THE BLOWER HOUSING REMOVED. DO NOT REMOVE CONNECTOR WIRES. YELLOW
RED NOTE: D. proceed to make an A. 15) Continuity should exist in one direction only.C.C.
BLACK LEAD 5 AMP A. To do this. / 5 Amp A.C.0 Volts A. output connector at the wiring harness and connect the probes from an A. Disconnect the red D. With the engine running. voltmeter to the wire terminals at the regulator-rectifier (diag. The yellow wire provides the A.C. and the regulator-rectifier must be brought outside of the blower housing.C. .C.28. Use the procedure for diode replacement found in the 3 AMP alternator test (diag. . .P.5 AMP D. Alternator
This unit combines a 3 Amp D.C. the minimum values should read: 2500 R.
15
43
. OUTPUT MUST BE DISCONNECTED TO PERFORM A.M. 3000 R. voltage for the lighting circuit. A wire harness( part # 36588) may be added to the 3 Amp D.23.
A. 5 Amp A.

C. If the system fails to charge a known good battery. VOLTMETER
21 45
.C.M. proceed to make an A.0 Volts A. If a known good battery fails to maintain a charge.
RED
DIODE
YELLOW
19
7 Amp D.Models OHV 13.
D. the regulator and rectifier are combined in one solid state unit mounted under the blower housing of the engine. Keep the A.0 Volts A.C.M. 21) CAUTION: AT NO TIME SHOULD THE ENGINE BE STARTED WITH THE BLOWER HOUSING REMOVED. 3300 R. . . the regulator-rectifier is defective. . voltage test.P. 20).M.P.C.P.0 Volts A.C.C.17. and the regulator-rectifier must be brought outside of the blower housing. .C.P. Test procedures for all types are the same. If the alternator puts out the minimum A. . .C. To do this. Various types of regulator-rectifiers have been used on different applications.P.P. If the minimum readings are noted.16.5 . voltage check cannot be made with this system. 3000 R.GREEN
20
INSERT PROBES INTO CONNECTOR SLOTS DO NOT REMOVE CONNECTOR WIRES
CAUTION: BLOWER HOUSING MUST BE INSTALLED WHEN RUNNING ENGINE
YELLOW
RED
A. 3000 R.C. .19. CHECKING THE SYSTEM: An open circuit D. 3600 R.M. A.C.21.M. regulator styles are not interchangeable (diag.C. voltmeter probe the regulator as shown (diag.M.C. the alternator is okay. However.23.0 Volts A. voltage from lead to lead should be: 2500 R.P.C. 3600 R.0 Volts A. Alternator System RegulatorRectifier Under Engine Housing
In this system.24.21. With engine running. If low or no voltage is experienced. replace the diode. minimum A.0 Volts A.C. OUTPUT LEAD-RED MAGNETO GROUND . voltage.C. the blower housing must be removed.C.C. Install the blower housing with the regulator-rectifier outside the housing.17 (Read between Engine and Diode)
2500 R. With an A. replace the alternator.M. leads attached to the regulator-rectifier.5 Volts A.

M.0 Volts A.C.C.P.M. 24).. the alternator is defective.C. voltage check using the applicable procedure. Connect a jumper wire from the metal housing (or other terminal) to a negative battery terminal.P. If a known good battery fails to maintain a charge. With the engine running. the charging system and the regulator can be checked using a voltmeter.C. OUTPUT YELLOW
A. the solenoid can be checked by removing the electrical plug-in at the base of the solenoid.C. voltmeter to the wire terminals at the regulator-rectifier. OUTPUT TEST. replace the regulator (diag. Disconnect the negative jumper lead and the plunger should return to the extended position.C. the voltage reading should increase from the noted battery voltage but not exceed 15 Volts D.C.C. .31.16. proceed to make an A.M. Place one lead of the A. OUTPUT MUST BE DISCONNECTED TO PERFORM A. Note the battery voltage.10 Amp A. 3000 R.P.5 Volts A. Start the engine.21 Volts A.P.C. See Chapter 9 for "Disassembly Procedure".C.M. Place the other lead to engine ground (diag. Almost immediately the engine should shut down. If no voltage increase is noted.M. 46
23
SINGLE
DOUBLE
24
. voltage is noted during the check.C.C. . proceed to make an A.C. OUTPUT .
AMMETER REGULATED D.0 Volts A.
A.C. . With the engine running. output check. 23).
22
16 Amp Alternator System with External Regulator
CHECKING THE SYSTEM: An open circuit D. the alternator assembly is defective.M. Replace if necessary (diag. from the battery positive terminal to the (or one) solenoid terminal. . the alternator is operating properly. Test the solenoid off the carburetor by applying 12 volt D. If the battery voltage exceeds 15 Volts D. or the proper minimum A. 3000 R.
D.C. The plunger should retract the full travel distance.C.26.C.RED
SOLENOID GREEN MAGNETO GROUND FUSE
BATTERY
LIGHT SWITCH
VOLTAGE REGULATORS
If a known good or load tested battery fails to maintain a charge. Disconnect the red D.C.0 Volts A.
FUEL SHUT-DOWN SOLENOIDS
If the engine is running. Set the voltmeter on the 0-20 Volt D.C. If less than above output. minimum values should read: 2500 R.P. minimum values should read: 2500 R.C.C.0 Volts A.22. Alternator
CHECKING THE SYSTEM: Unplug the connector at the wiring harness supplied by the OEM.C. Proceed to make an A. If less than the above values are noted. voltmeter on the center plug of the connector. OUTPUT YELLOW
RED NOTE: D. if not replace the solenoid. 3600 R.C.P.20. 22).C. output connector at the wiring harness and connect the probes from an A.C. . If the minimum values are noted. voltage test. 3300 R. voltage check cannot be made with this system. . scale and connect the probes across the battery terminals.

A bright blue spark should be seen at the tester. Place the speed control in the run position. If spark occurs now. Test by turning the engine over with the oil level below the add mark. Install a gap type tester connected to the spark plug wire and a good engine ground. replace the indicator light. replace the ignition module. and the oil level at the full mark. Remove the spark plug wire from the spark plug.LOW OIL SHUTDOWN SWITCHES
Check the LOS switch while it is in the engine.
FLOAT SWITCH
25
LIGHTED ENGINE ON/OFF ROCKER SWITCH W/LOW OIL SHUTDOWN
INDICATOR LIGHT
TERMINALS (3)
27
26
ENGINE ON/OFF ROCKER SWITCH
TERMINALS (2)
SPACER
28
47
. The engine must be level. If not. replace the LOS switch. If no spark is seen. If the indicator light does not flash. the indicator light will flash if the oil level is at or below the add mark and the engine is turned over while attempting to start. Spin the engine over using the electric or recoil starter. If equipped. Reinstall the blower housing and spin the engine over. remove the blower housing and disconnect the LOS lead from the ignition module.

i. (. only replaced.
ELECTRIC STARTER SERVICE
30
This section covers the service procedures for the 12 and 120 volt electric starters. If continuity is found or the tractor oil pressure indicator light is on or comes on at low engine RPM's. but procedures and tests apply unless otherwise stated. Remove the armature. For diagnosis of the starting circuit see Electrical Starter Troubleshooting in this chapter. Use teflon-type pipe sealant on the sensor threads to prevent oil leakage when reinstalling (diag. Place the keyswitch in the run position.700 bar). gear. Slide off the cap assembly. remove the sensor and check engine oil pressure with a master oil pressure gauge.)
BENDIX ASSEMBLY RETAINING RING DUST COVER THRUST WASHER RETAINER & SPRING BRUSHES
GASKET ARMATURE
31
48
. The response time of the sensor is between 5 and 15 seconds with 13 volts D. scribe a line across the cap assemblies and armature housing to aid in reassembly. and drive nut. 29). the "O" rings on each end of the housing must be replaced. If internal service is necessary (non-CSA) starters only. an internal engine problem exists (diag. place the armature into the brush end of the frame first.LOW OIL PRESSURE SENSOR
Test the sensor on a running engine using an ohmmeter or continuity tester with one tester lead connected the sensor terminal (with lead wire removed) and the other to an engine ground. Illustrations may not be identical in configuration to the starter being serviced. anti-drift spring. Lower battery voltage will result in a longer response time.i. 8. Inspect and replace as necessary. 30). Use the reverse procedure for assembly. Remove the two or four retaining nuts from the through bolts holding the cap assembly. Slide off the spring retainer.s. Remove the plastic dust cover on the bendix end (diag. The terminal insulator slides out of the commutator cap (some models).s. 2. The indicator light should come on with the tip of the sensor in air and go off when oil covers the sensor tip. 6. Push down the spring retainer and remove the retainer ring. If a starter is serviced. ( For ease of assembly. see the section "Inspection and Repair" later in this chapter. If lower than 10 p. 5. 7.700 bar). Starters labeled UL listed/ CSA approved are serviceable. Starters labeled CSA cannot be serviced. 3. An open circuit should be found with the engine running and continuity should exist when the engine is shut off.C. Remove the sensor from the engine and attach the electrical plug. 4.
29
LOW OIL SENSOR
This sensor must use a # 194 bulb in series with the sensor for proper operation and to prevent sensor damage. 31).
12 VOLT or 120 VOLT ELECTRIC STARTERS
1. Attach a jumper lead from an engine ground to the threaded portion of the sensor. (. at the battery. The oil pressure of a running engine should be above 10 p.

Grasp the thru bolts using a vise grip positioned as close to the flanged end as possible to prevent thread damage. Note or mark the brush card in the starter housing. it should be washed in solvent (rubber parts cleaned in soap and water) to remove dirt and grease. The brushes and brush card holder should be checked for wear. none should exist (diag. 3. 4. Remove the end cap and the thrust washer. followed by the two thru bolts. Scrape the insulating varnish off the last 1/2" (12. If the gear does not engage or slips. 3. Install and tighten the drive end thru bolt nuts. 9.
FIELD COIL CONNECTORS
FIELD COIL CONNECTORS
BRUSH SPRINGS 12 VOLT
CONNECTION POINT OF POWER CORD LEADS
32
120 VOLT
33
34
35
Brush Card Replacement
1. While rotating. Install the thru bolts while checking to make sure the bolts go thru the ground brush eyelet terminals. Use a needle nose pliers or vise grip to hold the woven brush lead close to the connector while soldering. 35). The field windings can be checked using a continuity light or ohmmeter. This prevents solder and heat from flowing up the brush lead. Remove the nuts holding the end cap in place. and remove the brush card assembly. With the armature in place and the brushes engaging the commutator surface. Notice the position of the brush ground eyelet under the thru bolt flange. Install the thrust washer on the end of the armature and the install the starter end cap. and no continuity should exist between the field coil connections and the starter housing (diag.Inspection And Repair
1. Check for continuity between the copper commutator bars and the iron of the armature. Note or mark the position of the connectors of the brush wires. Remove the two nuts holding the driving end cap in place. 8. 5. 2. but do not overtighten. 6. check the brushes for wear. Rotate the armature by hand to check for binding before installation on the engine. Brushes should be replaced if the brush wire approaches the bottom of the brush holder slot. Secure the cap with the locking nuts and tighten the nut on the starter terminal post. 32 & 33). Attach one lead to each field coil connection. Brush springs must exhibit enough strength to keep tension on the brushes and hold them on the commutator. polish the commutator bars using a piece of 00 sandpaper (diag. and dried before reassembly. 7. 49
. Insulate the crimped connection nearest the starter terminal post using electrical tape or heat shrink tubing. Install the armature into the housing while spreading the brushes.7 mm) of the solid field wires. Replace parts as necessary. Also check the armature and drive nut splines for wear or damage. Loosen but do not remove the two nuts on the starter terminal post. 4. Insert the new brush card into position while guiding the solid field wires through the proper slots in the brush card. 34). 2. The armature should be checked for glazing or wear. Use a wire cutter to clip the solid field wires as close to the connectors as possible. Recut the commutator bars to a depth equal to the width of the insulators between the bars. Clean the accumulated dirt off all starter parts. Route the wires to prevent damage during assembly. The pinion gear parts should be checked for damage or wear. If necessary the armature can be turned down in a lathe. Remove the armature and driving cap assembly. Continuity should exist between each field coil connection. Light pressure and back and forth movement should be used. Crimp and solder the brush leads to the solid field wires.

1). On electric start systems the starter is energized by an ignition/start switch or a two motion control. A specified foot probe must not contact the blade when applied completely around the entire blade housing. This alternative can be used with engine mounted brake systems and typical bail controls.CHAPTER 7 FLYWHEEL BRAKE SYSTEMS
GENERAL INFORMATION
Tecumsehs brake systems are required to meet compliance standards which has become a federal law as of June 30. Use of a recoil starter with the rope handle on the engine as opposed to within 24 inches (61 cm) of the operator position.P. The blade must stop within three seconds after the operator lets go of the engine/blade control bail at the operator position and the engine is stopped. 1982. Tecumsehs flywheel brake system provides consumer safety by killing the engine and stopping the lawnmower blade within three seconds after the operator releases the engine/blade control bail at the handle of the lawnmower. the engine/blade control bail must be applied. at the same time the ignition system is grounded out (diag. the recoil starter rope must be pulled to start the engine (diag. Listed below are two methods used by original equipment manufacturers to meet compliance standards. This method is acceptable if the mower deck passes the 360 degree foot probe test. The blade must stop within three seconds after the operator lets go of the blade control bail at the operator position and the engine continues to run. On nonelectric start systems. This action pulls the brake pad away from the inside edge of the flywheel and opens the circuit to the ignition ground out terminal. Starter rope handle is either on the engine or on the equipment handle.M. 2.
GROUND CLIP IGNITION GROUND WIRE
GROUND CLIP
IGNITION GROUND WIRE
BRAKE PAD BRAKE "ON"
1
BRAKE "OFF"
2
50
. or Service Bulletin # 107 to determine the correct engine speed or blade tip speed.
OPERATION
In the stop position the brake pad is applied to the inside edge of the flywheel. Consult microfiche card # 30. This system is available on recoil and electric start models. the Plus 1 or Parts Smart Look-up system. In order to restart the engine. Use of the blade brake clutch in conjunction with a top mounted recoil starter or 12 volt electric starter. 1. 2). The engine stopping time is affected by the engine R.

51
. and a tension spring (diag. This stops the solid state module from firing the spark plug (diag. The control cable transfers the motion of the engine/ blade control bail to the brake system. The wire is connected to the ignition ground out spade on the solid state module. If there is a electric starter switch used to start the engine. The ignition ground terminal is a plastic block with a wire extending out of it. The brake lever contacts the wire of the ignition ground terminal when the engine/blade control bail is released. 3). Remove the necessary components using steps 1-8 as outlined in Chapter 9 under "Disassembly". 3). and the ignition module is grounded. the interlock switch acts as a safety switch and will not allow the starter to crank unless the engine/blade control bail is depressed. The interlock switch is a push button switch that is activated by the brake lever when the engine/blade control is actuated. an ignition kill switch.
GROUNDING CLIP POSITION
TOP VIEW
LINKAGE
BRAKE PAD
3
Ô
MOUNTING HOLES MECHANISM FULL DOWN BEFORE SCREWS TORQUED
Ô
4
ELECTRIC START INTERLOCK SWITCH
SERVICE
Service on part or all of the flywheel brake assembly will require a partial disassembly of the engine to allow the flywheel and brake bracket to be removed. Where a two motion control is used the interlock switch is utilized as the starter switch.COMPONENTS
The brake bracket assembly consists of a replaceable brake lever and pad. The brake spring supplies the pressure to the brake lever and brake pad to stop the flywheel. Late production brake brackets are serviced as a complete assembly.

Rehook the link. Make sure the button on the starter interlock switch is completely depressed when the control is fully applied. rehook the short end of the spring and continue to reassemble the brake system in the reverse order of disassembly. be sure the slotted holes in the brake bracket are all the way down on the fasteners. check for less than 3 second stop time. be certain that the screw length is not too long as to prevent free travel of the lever. No continuity should exist when the button is released. Slide the pad lever from the shaft and unhook the link. continue by removing the alignment tool. On serviceable brake brackets. Remove the E clip from the brake pad shaft.
GROUNDING CLIP POSITION
TOP VIEW
LINKAGE
STARTER INTERLOCK SWITCH
The engine/blade control must close the interlock switch before the starter can be engaged. If the switch fails replace the switch (diag. 8). If the pad is contaminated. or if there is less than . The brake pad is bonded to the brake lever and must be replaced as an assembly. Continuity should exist between the two terminals when the interlock switch button is completely depressed. Use the self-tapping screws supplied with the new switch to make threads in the bracket. Remove the rivets from the back side of brake bracket. 6). Insure that all electrical connections are clean and secure (diag.
IGNITION GROUNDOUT TERMINAL
Inspect the terminal grounding wire for proper alignment and contact with the brake arm.
SCREW END MUST NOT BLOCK LEVER ACTION CABLE CLAMP SCREW
7
BRAKE BRACKET REPLACEMENT
When installing a inside edge brake bracket assembly. 7).060" (1. Disconnect the wires off the switch before performing a continuity check. 5). This will properly align the brake bracket to the flywheel brake surface (diag. install the "E" clip. To replace the interlock switch. To check the interlock switch. Be careful not to overtighten the screws as switch breakage can occur (diag. 6). Inspect the brake pad for dirt.
BRAKE PAD
5
Ô
MOUNTING HOLES
MECHANISM FULL DOWN BEFORE SCREWS TORQUED
Ô
6
ELECTRIC START INTERLOCK SWITCH
CONTROL CABLE
If replacing the cable conduit screw with a screw other than a service part replacement. The cable must provide enough travel so the brake will contact the flywheel.BRAKE BRACKET ASSEMBLY
Late production brake brackets are serviceable only by installing a complete brake bracket assembly. When completed.
MOUNTING HOLES
Ô Ô
MECHANISM FULL DOWN BEFORE SCREWS TORQUED
8
52
. Some slack should exist in the cable adjustment to compensate for brake pad wear (diag. replacement is necessary. Release the spring tension by unhooking the short end of the spring from bracket with a pliers. carefully grind the heads off of the rivets that fasten the interlock switch to the brake bracket.524 mm) thickness of brake pad material at the pad's thinnest point. oil or grease contamination. install the brake lever and pad assembly. Install the interlock switch onto the brake bracket in the proper position and secure the switch to the brake bracket with the machine screws supplied. use an ohmmeter or continuity light to perform a continuity check.

a silicon controlled rectifier. As the magnet continues to rotate. This solid state (CDI) module is protected by epoxy filler from exposure to dirt and moisture.
OPERATION SOLID STATE IGNITION SYSTEM (CDI)
As the magnets in the flywheel rotate past the charge coil. If necessary. electrical energy is produced in the module. key and the spark plug are located in a encapsulated ignition module.
COMPONENTS
The solid state module is a complete unit that includes the laminations and spark plug wire. The outside electrode is grounded and secured to the threaded sleeve. The spark plug is made up of two electrodes. the correct replacement module should be found using the Master Technician's Parts Manual. The modules look similar but are not interchangeable. trigger coil. NOTE: Always consult parts manual for correct plug and reach. 200 volts) until it is released by an electrical switch (SCR). A large voltage from the module arcs the air gap which causes a spark and ignites the air-fuel mixture in the cylinder (diag. The two are separated by an air gap which creates a resistance.000 volts.2). The energy is stored in the capacitor ( approx. This is an all electronic ignition system with all the components located outside the flywheel. high tension lead. 1). allowing the energy stored in the capacitor to flow to a transformer where the voltage is increased from 200 volts to 25. This system requires no maintenance other than checks of the high tension lead and spark plug. and a spark plug. Everything except the flywheel magnets. it passes past a trigger coil where a low voltage signal is produced. This low voltage signal closes the SCR switch. charge coil. pulse transformer. This voltage follows along the high tension lead to the spark plug where it arcs across the electrodes and ignites the air-fuel mixture (diag. capacitor.
STANDARD PLUG OHV
1
2
53
.CHAPTER 8 IGNITION
GENERAL INFORMATION
Overhead valve four cycle Tecumseh engines use solid state capacitor discharge modules to provide high voltage to fire the spark plug. The solid state ignition system consists of flywheel magnets and a flywheel key. The center electrode is insulated with porcelain.

NOTE: Always replace flywheel keys by Model and Specification Number. the magnetic strength is satisfactory (diag. Check the air gap between the flywheel magnets and the laminations of the ignition module. or booklets offered by the Tecumseh Products Co. Remove the blower housing. 3
TESTING PROCEDURE
1. It should be .05 mm) of the magnets.05 mm)
MAGNETS
4
4. 3). Examine the ignition module and lamination assembly for cracks in insulation or other damage.The flywheel with magnets provide the magnetic flux (or field) which is necessary to induce voltage and trigger the module to provide spark. Check the operation of the ignition module using an approved tester following the instructions furnished with the test unit. Try to start and run the engine. Hold a screwdriver at the extreme end of the handle with the blade down. Ignition modules are permanently attached to the lamination and must be serviced as an assembly. excessive carbon buildup. or partially sheared. 4). Check for spark using a commercially available spark tester and following the tester's recommended procedure. Engine and Transmission Group Service Division. If the screwdriver blade is attracted to the magnets.030" (. If the engine will not start or run properly proceed to step #3. 2.
54
. the engine will not start or can be difficult to start (diag. Attach the spark plug wire to the spark plug tester and ground the tester as in step #1. If spark occurs. 7. 5. Tecumseh has some keys that look similar but affect ignition timing. which would cause shorts or leakage of current.
3/4" (19. disconnect the ignition grounding lead at the ignition module. 6. move the blade to within 3/4 inch (19. Check the flywheel magnets for the proper strength using this rough test. and proper . If a flywheel key is sheared. safety interlock switches.762 mm) air gap setting. Check the spark plug for cracks in the porcelain. 3. Reinstall the blower housing and crank the engine over.3175 mm) or use gauge part # 670297. Replace if questionable. The flywheel key locates the flywheel to the crankshaft in the proper position for ignition timing. or electrical wiring for shorting to ground.0125" (. pitted or burned electrodes. check the ignition switch.

8. Weak ignition system. If a torque wrench is not available. BLOW OUT THOROUGHLY WITH COMPRESSED AIR. Improper fuel. Poor grade of gasoline.
GAP GAUGE (670256)
SPARK PLUG SERVICE
Spark plugs should be removed. 3. Partially closed choke shutter. 5
CONDITIONS CAUSING FREQUENT SPARK PLUG FOULING
1. Check the air gap with a spark plug gap gauge and adjust accordingly. 6. 9.
Normal
Carbon Deposit
Worn
Oil Deposit
6
56
. Faulty piston rings.SERVICE
To remove the ignition module or the flywheel from the engine. 2. Restricted exhaust system. Incorrect spark plug gap. AND USING EYE PROTECTION. USE A SOLVENT AND A WIRE BRUSH TO CLEAN. or 1/2 of a turn further if using a new spark plug. Incorrect spark plug. see Chapter 9 under "Disassembly". Replace the plug if the points on the base of the plug are pitted or burned. When replacing a spark plug consult the parts breakdown for the correct spark plug to be used in the engine being serviced. 5). 10. Carburetor setting is too rich or the air cleaner is restricted. Set the spark plug gap at .5 Nm) torque. and use a spark plug wrench to turn the spark plug 1/8 to 1/4 of a turn further if using the old spark plug. and adjusted periodically. cleaned. or the breather is restricted.762 mm) (diag. NOTE: DO NOT USE A SAND BLASTER TO CLEAN PLUGS. 5. screw the spark plug in as far as possible by hand. Install the spark plug in the engine and tighten it to 180 inch pounds (20.030" (. Oil level is too high. 4. MICROSCOPIC PARTICLES LEFT IN THE PLUG CAN SCORE THE ENGINE CYLINDER DURING OPERATION. or if the porcelain is cracked anywhere. When reinstalling the plug make sure it is clean of all foreign material. 7.

or spark plugs. the air gap is set correctly and the air gap check is completed (diag. A partially sheared or the wrong flywheel key can cause kickback.IGNITION TIMING CHECK
In order for an engine to run effectively and efficiently. If the mixture is ignited too soon. flywheel keys. The air gap check consists of having the proper . This position is known as Before Top Dead Center (BTDC). loss of power. 7). If none are found. part # 670297 between the flywheel magnets and the laminations of the module while tightening the mounting screws to the proper torque. the spark must ignite the compressed air-fuel mixture when the piston is in a specific position to deliver maximum power. kickback can be experienced due to preignition. Use flywheels with cooling fins that are broken off.
57
. If the mixture is ignited too late. Check the flywheel key if one of these symptoms exist. See Chapter 9 under "Service" for the disassembly procedure. Attempt to reglue the spark plug lead back into a solid state module.1 meters) of an unshielded welder. or an inability to start the engine with a good spark. Remove the air gap gauge and rotate the flywheel to check for any possible striking points. Use a standard business card as an air gap gauge. loss of power can be experienced due to retarded spark.3175 mm) air gap gauge.3175 mm)
7
SERVICE TIPS DO NOT:
Interchange flywheels.
. Timing on a solid state module is not adjustable.0125" (. Store a solid state module within 20 feet (6.0125" (.

2). The crankshaft makes two revolutions for every camshaft revolution. drawing the air-fuel mixture from the carburetor into the cylinder area above the piston (diag. The intake valve is open and the exhaust valve is closed. The expanding gases force the piston down (diag. 1
2
3
4 58
. The piston is traveling downward creating a low pressure area. EXHAUST. As the piston reaches Bottom Dead Center (BDC) the intake valve closes. counterbalance systems. the four cycle process will begin again as the piston moves downward and the intake valve opens. 1. the piston has moved to Top Dead Center (TDC) ready to take the full combustive force of the fuel for maximum power during downward piston travel. INTAKE. not all engines with cast iron cylinder liners are identified as XL or XL/C. 4). crankshaft. compressing the air-fuel mixture trapped in the combustion chamber due to both valves being closed (diag.
OPERATION 4-CYCLE ENGINE THEORY
All 4-cycle engines require four piston strokes or cycles to complete one power cycle. igniting the air-fuel mixture. breather. COMPRESSION. 1). the spark plug fires. 3. During this piston stroke both valves remain closed. After the piston reaches Top Dead Center (TDC). POWER. The engines identified by decals or model as XL (Extra Life) or XL/C (Extra Life / Commercial ) are made using aluminum alloy diecast around a cast iron cylinder liner. flywheel. piston and rod assemblies. and lubrication systems. 2. The piston then rises.CHAPTER 9 INTERNAL ENGINE AND CYLINDER
GENERAL INFORMATION
This chapter covers the cylinder block. All Tecumseh engines covered in this manual are four cycle engines with the valves in the engine head. As the piston reaches the Before Top Dead Center (BTDC) ignition point. valve train. The engine camshaft gear is twice as large as the mating gear on the crankshaft to allow proper engine valve timing for each cycle. cylinder head. However. camshaft. In the time it takes to ignite all the available fuel. The governors and the governor systems are covered in Chapter 4. the exhaust gases are forced out (diag. 3). 4. The crankshaft position is designated as either horizontal or vertical as the engine rests on its base. As the piston starts to the top of the cylinder. The exhaust valve opens. The flywheel or the equipment load on the crankshaft provides the inertia to keep the engine running smoothly between power strokes. cylinder cover.

A crankshaft drilling also provides oil to the crankpin journal on engine models OHV 13.5 -16. The oil dipper is either bolted on or may be cast on to the cap with one of the rod bolts (diag. which in turn drives the second counter balance shaft. Oil is pumped from the bottom of the crankcase. On all Tecumseh vertical shaft 4-cycle engines. 5).
SPRAY MIST HOLE FLAT
DIPPER SPRAY MIST HOLE CRANKCASE PASSAGE PLUG CRANKSHAFT OIL PASSAGE
6
MAIN BEARING OIL GROOVE
CAMSHAFT DRILLED CAMSHAFT PASSAGE BARREL TYPE LUBRICATION PUMP
7
ASSEMBLE PUMP HOUSING WITH INSIDE CHAMFER TOWARD CAMSHAFT GEAR
8
OIL DRAIN HOLE
NOTE: INSTALL OIL PUMP AFTER THE SUMP IS ON
9
5
DRIVE GEAR
COUNTERBALANCE SYSTEMS
Some Tecumseh engines may be equipped with an Ultra-Balance® counterbalance system. the eccentric moves the barrel back and forth on the plunger forcing oil through the hole in the center of the camshaft. Oil under pressure lubricates the top crankshaft main bearing and camshaft upper bearing (diag. see " Engine Assembly Procedure " in the Service section of this chapter. The rotary pump is driven by the camshaft. This system uses a single weighted shaft that is driven off the crankshaft. 9). All vertical shaft engines use a positive displacement plunger oil pump or a rotary oil pump. An oil dipper on the connecting rod splashes oil in the crankcase to lubricate all internal moving parts. 10). It uses a lobed gear in a rotating ring to provide positive oil displacement (diag. This shaft's function is to counteract the imbalance caused by the counterweights on the crankshaft (diag. 7). up through the camshaft and over to the top main bearing. For timing of either counterbalance system. and other internal parts (diag. As the camshaft rotates. The ball on the end of the plunger is anchored in a recess in the cylinder flange (diag. connecting rod. A gear on the crankshaft drives the counterbalance with the thicker gear. the oil is sprayed out under pressure through a small hole between the top camshaft and crankshaft bearing to lubricate the piston. 8).
COUNTERBALANCE SHAFT
GOVERNOR FLANGE CAMSHAFT
10 59
. 6).5. A dual shaft counterbalance is also used on some engine models.LUBRICATION SYSTEMS
The lubrication system used with all Tecumseh horizontal crankshaft engines covered in this manual utilize a splash type system. The plunger style oil pump is located on an eccentric on the camshaft.

COMPONENTS
The cylinder block houses the piston, crankshaft, and along with the cylinder cover all the internal components. The block is a one piece diecast aluminum alloy cylinder casting which may have a cast iron liner (diag. 10). The piston transmits the force of the burning and expanding gases through the connecting rod to the crankshaft. The piston rings provide the seal between the cylinder wall and the piston. The rings keep the combustion pressures from entering the crankcase and also wipe the oil off the cylinder wall and return it to the sump. The connecting rod assembly is the link between the piston (piston pin) and the crankshaft. The cylinder head is a one piece aluminum alloy casting that is bolted to the top of the cylinder block. The overhead design contains all of the valve train except for the camshaft, lifters, and push rods. The crankshaft converts the up and down piston movement to the rotational force (torque) by an offset crankpin or rod journal. The camshaft lobes push the lifters at the proper time to allow air and fuel in and exhaust out of the cylinder. Teeth on the camshaft gear time the camshaft to the crankshaft. The valves allow air-fuel mixture to enter the cylinder and exhaust gases to exit. The valves provide a positive seal when closed. The valve springs return the valves to the closed position and must be strong enough to maintain valve lifter and cam lobe contact. The valve retainers lock the spring to the valve stem. The valve lifters maintain contact on the camshaft, move the push rods to pivot the rocker arms and move the valves. The crankcase breather is a one way check valve that allows air out and prevents air from coming in. It allows the engine to develop a partial vacuum in the crankcase during operation. The cylinder cover provides the bearing surface for the power take off (P.T.O.) end of the crankshaft and camshaft. This bolted on cover is removed to provide access to all internal components. The oil pump (vertical shaft only) consists of a steel plunger and a nylon or aluminum housing that rides an offset on the camshaft. The rotary pump consists of a lobed gear in a rotating ring that is driven by the camshaft. The flywheel provides the mass to smooth the effects of one power stroke every other crankshaft revolution. Flywheels are made of aluminum alloy or cast iron. The flywheel fins act as a fan to cool the engine.
CHAMPFER UP TOWARD CAM SHAFT

ROTOR

OIL SEAL REMOVED ROTARY PUMP PUSH ROD GUIDE PLATE RING SNAP RING

PUSHRODS LIFTERS

CAMSHAFT VALVES

CRANKCASE BREATHER CRANKSHAFT FLYWHEEL

10

60

ENGINE OPERATION PROBLEMS

ENGINE KNOCKS

OVERHEATS

SURGES OR RUNS UNEVENLY

Associated equipment loose or improperly adjusted

Excessive engine loading

Fuel cap vent obstructed

Check for excessive carbon in combustion chamber

Low oil level or wrong viscosity oil

Dirty carburetor or air filter

Loose flywheel examine key, key way and proper flywheel nut torque

Cooling air flow obstructed or clogged cooling fins

Carburetor improperly adjusted

Ignition timing or incorrect spark plug

Carburetor improperly adjusted or improper RPM setting*

Governor sticking, binding or improper RPM setting

Loose or worn connecting rod

Ignition timing or incorrect spark plug

Carburetor linkage, shafts or shutters sticking or binding

Worn cylinder

Carbon in the combustion chamber

Intermittent spark, check ignition or incorrect spark plug

EXCESSIVE OIL CONSUMPTION

Lean carb setting causing overheating (adjustable carb)

Oil level above full

Piston rings worn

Wrong viscosity oil

Worn or glazed cylinder

Excessive engine speed

Valve guides worn excessively

Engine cooling fins dirty causing overheating

Breather damaged, dirty or improperly installed

Damaged gaskets, seals or "O" rings

61

ENGINE OPERATION PROBLEMS

ENGINE MISFIRES

ENGINE VIBRATES EXCESSIVELY

BREATHER PASSING OIL

Carburetor improperly adjusted

Bent crankshaft

Oil level too high

Wrong or fouled spark plug

Attached equipment out of balance

Excessive RPM or improper governor setting

Valves sticking or not seating properly

Loose mounting bolts

Damaged gaskets, seals or "O" rings

Ignition timing or incorrect spark plug

If applicable counter balance not properly aligned

Breather damaged, dirty or improperly installed

Excessive carbon build up

Piston rings not properly seated or ring end gaps are aligned

Improper Valve Lash Weak valve spring

Angle of operation too severe

LACKS POWER

Air intake obstructed

Lack or lubrication or improper lubrication

Carburetor improperly adjusted

Exhaust Obstructed

Improper valve lash

Loss of compression (worn rings, blown head gasket)

62

Check the ignition timing. 6." 4.Service. Loosen the cap and retry engine operation. Make sure the engine is not being overloaded." 3. Visually check all linkages. Tighten the flywheel nut to the proper torque. See Chapter 3 under "Service. Replace if questionable. process less material). Remove the cylinder head and check for excessive carbon in the combustion chamber. loose bolts. Check the ignition timing.M. and the spark plug for proper reach and heat range (correct spark plug for the engine). Check for the proper valve lash using a feeler gauge." 4. See Chapter 10 under "Specifications". Check the engine R.P.P. Check for clogged cooling fins or obstructions to the air flow. replace if necessary. Remove the cylinder head to check for excessive carbon buildup or a leaking head gasket. Adjust as necessary. 5. settings found on microfiche card # 30 according to the engine model and specification number." 7. 4. Check for scoring or discoloration on the valve stem in the valve guide area. inspect. 6.
ENGINE OVERHEATS
1. 5. Check the engine R. Clean or replace as necessary. 3. Recut the valves and seats if questionable. Check the flywheel key and the flywheel and crankshaft keyway for wear or partial shearing. settings found on microfiche card #30 according to the engine model and specification number. See Chapter 3 under "Service. Add or replace as necessary. Check valve lash. Reset the carburetor following the adjustment procedure or clean the carburetor.TESTING ENGINE KNOCKS
1. Check the governor shaft. See Chapter 8 under "Service. Also check that the head gasket fit is correct. or pivot points for binding. connecting rod. 6.M.
SURGES or RUNS UNEVENLY
1. 5. or crankshaft key damage. Adjust as necessary. Check the internal components (piston. 2. setting using a vibratach or other tachometer and compare it to the R. limit operation speed. 63
. Reinstall and re-torque the bolts to the proper torque. Inspect the valves and valve seats for leakage. Check for intermittent spark. Check the oil level and viscosity. Replace or clean the air filter. 2.P. 2. Check the carburetor for correct adjustment or remove and clean the carburetor using tag wire and compressed air. Check the fuel cap to make sure it is venting. blade adapter. See Chapter 8 "Ignition . setting using a vibratach or other tachometer and compare it to the R. See "Valve Service" in this chapter. cylinder. Remove excess load (sharpen blades. Remove. clean and reinstall." 5.P. See Chapter 3 under "Service. 4. Check the carburetor adjustment or clean the carburetor. Check the spark plug for the proper application or a fouled condition. Replace if any damage is evident. 3. throttle shaft.
ENGINE MISFIRES
1. Check for carbon buildup in the combustion chamber. 2. Remove the blower housing. Check the ignition module operation using a gap type tester installed between the high tension lead and spark plug.M. Check for the correct ignition module air gap. 3. crankshaft journal) for excessive clearance. or crankshaft coupler for loose fit.M. Check the blade hub.

or "O"-rings. 8.
11
EXCESSIVE OIL CONSUMPTION
1. Follow the compression tester's procedure. dirty condition. or leaking valves. seals.
BREATHER PASSING OIL
1. or "O"-rings. 3. Check the engine compression using a compression tester. Check the breather for damage. oil viscosity on the container of the oil being used. Check the valve guide clearance for excessive wear.P. External leaks may not be evident. and oil condition. leaking head gasket. setting using a vibratach or other tachometer and compare it to the R.M. Check the oil level. 64
. The oil return hole(s) must face down.ENGINE VIBRATES EXCESSIVELY
1. determine the cause of weak compression: worn rings. Check the engine compression using a compression tester. however.P. 6. 5. Remove the spark plug wire.P. 7. make sure the engine is not overfilled. square or a dial indicator. 2. overheating the engine. determine the cause of weak compression: worn rings. Avoid prolonged use at a severe angle. 2. 3.M. The computer parts lookup systems also have RPM information listed in each individual engine parts list. External leaks may not be evident. Check the oil level. or leaking valves. 4.M. Clean the cooling fins to prevent overheating. Blades or adapters must be removed. Check for leaking or damaged gaskets. Remove and check the attached equipment for an out of balance condition. Check for leaking or damaged gaskets. Check the carburetor setting causing a lean running condition. seals. Also verify that the viscosity rating on the container of the oil being used is to specification. Check the breather for damage. the leak may prevent the engine from achieving a partial crankcase vacuum.P.M. Check the engine crankshaft on the PTO end for bends using a straight edge. Check the engine R. however. 9.P. 3. 4. 2. dirty condition. Check the angle of operation. If the engine has weak compression. or improper installation. Adjust the high and low R. Adjust as necessary. or improper installation.M. as necessary.M. Follow the compression tester's procedure. Avoid prolonged use at a severe angle.P. Check the engine R. The oil return hole(s) must face down. Replace and fill to the proper level. Significant deflection will cause a vibration problem. 4. using a vibratach or other tachometer and compare it to the R. setting for excessive R. leaking head gasket. Check the engine mounting bolts. 6. the leak may prevent the engine from achieving a partial crankcase vacuum. make sure they are tight. settings found on microfiche card # 30 according to the engine model and specification number. Check the angle of operation. If the engine is equipped with a counterbalance shaft. If the engine has weak compression. settings found on microfiche card # 30 according to the engine model and specification number. 5.
2 and 4-CYCLE RPM SETTINGS
30
NOTE: MICROFICHE CARD 30 RPM'S ARE NOT ON PAPER NOTE: RPM SETTINGS CAN ALSO BE FOUND ON THE COMPUTERIZED PARTS LOOK UP SYSTEMS. check the gear timing to determine if the counterbalance is out of time.

If necessary. NOTE: DO NOT USE A JAW TYPE PULLER. See "Cylinder Head and Valve Train Service" in this chapter. 5. 8. 4.875 mm use part # 670314.
SERVICE DISASSEMBLY PROCEDURE
The following procedures apply to most engine models. 2. Actual procedure may vary. Drain the oil from the crankcase. Thread the appropriate flywheel knock-off tool (7/16" / 11. Check the engine valve lash. 2. then unthread it one complete turn. Check the flywheel key for partial shearing. Check the air intake for an obstruction (dirty filter. Check the oil level. Unplug the ignition kill wire from the terminal on top of the ignition module and unbolt the ignition module. oil viscosity on the container of the oil being used and oil condition. 14). 5/8" / 15.112 mm use part # 670103. 11/16" / 17. 1. 3. oil saturated filter. Compress the spring by moving the lever toward the spark plug end and when the hole in the lever aligns with the hole in the bracket secure the lever in this position with alignment tool part # 670298. screws. Drain or shut off the fuel supply. Replace the valves if necessary." 4. Fuel tanks may be held on with bolts. rotate the flywheel a half turn and repeat until it loosens (diag. Remove the air cleaner assembly.7 mm use part # 670169.
METAL HAMMER
SOCKET WRENCH FLYWHEEL
FLYWHEEL TOOL
12
KNOCK OFF TOOL
SCREWDRIVER TO RAISE FLYWHEEL
13
14 65
. washer. Reset the valves at the proper lash. Lift upward under the flywheel using a large screwdriver while avoiding contact with the alternator coils or magnets. 3. Relieve the compliance brake pressure on the flywheel if applicable. 1/2" / 12. 7. Check the exhaust port or muffler for a restriction preventing proper exhaust flow. 6. other debris). Recondition the valves and seats. Readjust the carburetor or remove the carburetor for cleaning. Check the valves for proper seating and valve guide clearance.LACKS POWER
1. Remove the flywheel nut. Remove the blower housing by first unscrewing the screw holding the dipstick tube to the blower housing and removing the remaining bolts holding on the blower housing.462 mm use part # 670329) on the crankshaft until it bottoms out. Locate the piston at Top Dead Center (TDC) on the compression stroke for easier valve train service. or some models require taps upward with a soft face hammer loosening the plastic tank wedges in the blower housing slots. 5. Check the ignition timing. 12). 7. 9. and tap sharply and squarely on the knock-off tool to break the flywheel loose. 6. Remove the spark plug. A flywheel puller (part # 670306) may be used on flywheels with cored holes (diag. Disconnect the high tension lead from the spark plug. Remove the fuel tank if it is attached to the engine. Use a part # 670305 strap wrench to hold the flywheel from turning (diag. See Chapter 3 under "Service. and starter cup. Replace and fill to the proper level. 13).

valve stems. 12. and retainer screw must be removed to allow the rocker box to separate from the head. Remove the rocker arm nuts or rocker arm bearings followed by the rocker arms.
15
66
. Remove the flywheel key and alternator if equipped. retainers. Remove the crankcase breather if necessary. retainers. with independent cylinder head and rocker box. OHV13. The push rod guide plate must be removed to access one of the head bolts. and the rocker arm retainer screw. head gasket and valves. Remove the muffler. Then place a 3/4" (19.05 mm) deep socket over the valve cap and strike the top with a steel hammer (diag. Remove the rocker arms by loosening the two locking nuts or allen head screws. 15). OVRM and OHV 11-13 use a 1/2 wrench. Notice the "O"rings used to seal the rocker box . rocker arm studs. adjusting nut. On engine models OHM. Remove the head bolts. head. guide plate. Mark the hookup points or diagram the linkage arrangement to aid in reassembly. spacer if equipped. Be careful not to bend or damage the linkage when removing. the valve springs. push rods. Next to prevent valve or piston damage turn the piston down in the cylinder.10.17 use a 3/16" allen and 1/2" wrench. OVXL and OHV. and push rods. Remove the jam nut. caps. and push rod tubes. 11. guide plate. Use a 3/16" Allen wrench and a 7/16" wrench on OHH. and baffle plate. 13. head bolts. 14. OHSK120. Remove the rocker arm housing. head. and the carburetor. and head gasket. rocker arm bearings.5 . Remove the intake pipe. Remove the cap. and valve springs. OVM. Remove the head by first removing the valve cover. NOTE: ON SOME OHV ENGINES THE EXHAUST PUSH ROD CAN ONLY BE REMOVED AFTER THE HEAD IS OFF. YOU MUST HAVE IT BACK IN BEFORE REASSEMBLY. rocker arms. This action loosens the cap.

On all other overhead valve engine models. place a 3/4" (19. retainers. 18. Remove the lifters. Slide the large opening in the retainer toward the valve stem to remove (diag. turn the crankshaft to roll the reduction shaft gear off the crankshaft worm gear when removing the cylinder flange (diag. 15). Push the piston out the top of the cylinder bore. The valve springs must be assembled on the same valve they are removed from (diag. 17. rod cap.T. 20. 21). 16.O. 20). OHH engines with a ball bearing on the P. one at a time. remove any carbon from the top of the cylinder bore to prevent ring breakage. end of the crankshaft require the oil seal and the snap ring to be removed prior to the cylinder cover removal. For engines equipped with 8-1/2:1 gear reduction. 19).15. Align the timing marks on the camshaft and crankshaft gears and remove the internal components (diag. Remove the cap. and counterbalance shaft or gears if applicable. 17. This action loosens the cap. Remove the valves from the head on models OHH and OVRM by supporting the valves with fingers while compressing the valve springs. 19. Before removing the piston. 18.
WORM GEAR
OIL SLEEVE TOOL MOUNTING FLANGE OIL SEAL
16
GEAR
17
18
OIL SEAL REMOVED
SNAP RING
19
BEVELED TOOTH TIMING MARK
CRANKSHAFT GEAR
CAMSHAFT GEAR
20
21 67
. remove the auxiliary shaft from the cover by removing the retaining ring and sliding the shaft out of the washers and drive gear. Remove the cylinder cover or mounting flange using a seal protector positioned on the seal to prevent seal damage. 16. with thumbs.05 mm) deep socket over the valve cap and strike the top with a steel hammer. On engines equipped with 8-1/2 :1 gear reduction. The crankshaft must be free of rust or scale to slide the cover or flange off the crankshaft. and valve springs.

127 mm) oversize. and even with the piston pin as the piston would appear when assembled. Every fourth or fifth stroke. A rigid hone is recommended to "true" any cylinder irregularities.450 crosshatch pattern. Replace the piston and the piston rings with the correct oversize parts as indicated in the parts manual.P. A light honing oil should be used to lubricate and cool while honing. If cylinder oversizing is needed we recommend boring the cylinder. Check the main bearing for wear or scoring. If the cylinder bore is worn more than . Use a dial bore gauge or transfer gauge with a micrometer to accurately measure the cylinder bore. the oversize value will be imprinted in the top of the cylinder (diag. Clean the cylinder and crankcase with warm. Check the bore diameter every twenty or thirty strokes for size and a 350 .254-.508 mm) oversize. Start with coarse stones and center the cylinder under the drill press spindle. clean the stones with a wire brush when the hone is removed. Lower the hone so the lower end of the stones contacts the lowest point in the cylinder bore. You also may wish to contact a local machine shop.005" (. soapy water. out of round or scored.
.020" (. move the hone far enough to extend the stones one inch beyond the top and bottom of the cylinder bore. This service is offered by many Service Dealers. See "Crankshaft Bearing Service" in this chapter.05 mm) from the top and the bottom . rinse with clean water.M. Tecumseh recommends 380 grit for finish in a standard cross hatch. Chuck the hone in a drill press with a spindle speed of about 600 R. Rotate the adjusting nut so that the stones touch the cylinder wall and begin honing at the bottom of the cylinder. 22). Measure at 90 degrees to the piston pin.
68
. Measure in the piston travel area approximately 1/2" to 3/4" (12.CYLINDERS
Visually check the cylinder for broken or cracked fins or a scored cylinder bore.010
22
To recondition a cylinder. 45 degrees to the piston pin.010
. If the stones collect metal. and dry thoroughly. it should be replaced or re-sized to . Move the hone up and down at a rate of 50 strokes per minute to avoid putting ridges in the cylinder wall. In some cases engines are built with oversize cylinders. If the main bearing is worn or scored it can be replaced on some models. If the cylinder is oversize.010" or .7-19. use a commercially available hone of the proper size . Continue the cleaning procedure until a clean white cloth wiped on any internal surface reveals no honing residue or dirt.

Springs. OHSK50 . 26). Slight warpage can be corrected by placing a sheet of #400 wet /dry sandpaper on a precision flat surface and rubbing the head gasket surface in a circular pattern until the entire gasket surface shows evidence of sanding. Replace the springs if necessary.794 mm). When servicing the valves. a popping is heard through the intake or exhaust.CYLINDER HEAD AND VALVE TRAIN SERVICE
Check the cylinder head for warpage by placing the head on a precision flat surface. Valves marked "EX" or "X" are installed in the exhaust valve location. If warped in excess of .
1/32" (.127mm). If the spring has dampening coils. Valve lash (between the rocker arm and valve stem) should be set or checked when the engine is cold. A small amount of honing oil on the sandpaper will make it easier to slide the head. or when excessive valve train noise is heard. Always replace the head gasket and torque the head bolts in 60 inch pound (6. the valve face should be ground using a valve grinder to a 45 degree angle. The valve springs should be checked for both ends being parallel and the free length being at least 1. And Push Rods
The valves should be checked for proper lash.980" (50.7 Nm) increments in the numbered sequence torques in specification section (diag.D. OHSK80 .70
2 23 4
2
Valves.292 mm)
26
69
. inspect the corresponding rocker arm socket or valve lifter for wear. all carbon should be removed from the valve head and stem. 1. OVXL. OHM. sealing.105" (28.17. Valves marked "I" are installed in the intake valve location. If the valves have been checked and are in a usable condition. on the compression stroke (both valves closed). replace the head. See specification section.005" (. If after grinding the valve face the margin is less than 1/32 of an inch (. and OHV engines when the valves are removed for service. If the valves are unmarked.130 MARGIN 450 FACE
6
24
25
FREE LENGTH OVRM/OHH/ OHSK50-70 1. OHSK. Valve condition is critical for proper engine performance.794 mm) MINIMUM DIMENSION STEM
5
1
3
TORQUE SEQUENCE OHV 11 .105" (28.
3
1
5
4
TORQUE SEQUENCE OVRM / OHH.292 mm for OHM. Valve lash should be checked before removal of the engine head if any of the following conditions are experienced.067 mm) for OHH and OVRM engines. Valves are not identical. 23 & 24).C. The push rods should be checked for straightness and the ends for wear. The piston should be at T. OVM. an engine kickback is experienced. the valve spring should be installed with the dampening coils away from the valve cap and retainers (diag. the smaller valve (head) is installed in the exhaust valve location. If the push rod ends are worn or damaged. 25). Replace if necessary. and wear.980" (50.067 mm)
DAMPENING COILS LOCATED CLOSER TOGETHER THIS END MUST FACE TOWARD THE STATIONARY PART OF THE ENGINE (CYLINDER HEAD)
ALL OTHERS 1. the valve should be replaced (diag.

an oversize piston will be necessary.
30
EMISSION RINGS 1ST COMPRESSION RING 2ND COMPRESSION RING 3RD OIL CONTROL RING
31
70
. When installing new rings in a used cylinder. Replace the rings in sets and install the piston.010" (. replace the piston. Clean all carbon from the piston top and the ring grooves before measuring.254 mm) OVERSIZE PISTON
PISTON MEASUREMENTS ARE TAKEN AT BOTTOM OF SKIRT 900 FROM WRIST PIN HOLE
27
Piston Rings
After the cylinder bore diameter has been checked and is acceptable to rebuild. If the cylinder bore needs re-sizing. Use the piston upside down to push the ring down (diag.
INDICATES . 27).PISTONS. The rule to follow is an inside chamfer always faces up. rings. This procedure will assure correct piston ring end gap measurement. 30). Use a ring expander to remove and replace the rings. 31) will face down or towards the skirt of the piston. the cylinder wall should be de-glazed using a commercially available de-glazing tool or hone. Oversize pistons are identified by the imprinted decimal oversize value imprinted on the top of the piston (diag. Check the ring side clearance using a feeler gauge with a new ring. RINGS.
CYLINDER
PISTON PISTON RING
28
29
CHAMFER 1ST COMPRESSION RING 2ND COMPRESSION RING 3RD OIL CONTROL RING
Piston Ring Orientation
If the top compression ring has an inside chamfer. The expander (if equipped) end gap and the ring end gap should be staggered (diag. 28) and measure the gap with a feeler gauge. Place a new compression ring squarely in the center of the ring travel area. If scoring or deep scratches are evident. 29). Ring side clearance should also be checked with a feeler gauge when using new rings with an old piston (diag. NOTE: Always stagger the ring end gaps on reassembly. this chamfer must face UP. The ring end gap must be within the specification to have adequate oil control (diag. An outside notch (diag. Do not spread the rings too wide or breakage will result. The oil control ring can be installed with either side up. Visually inspect the piston skirt area for scoring or scratches from dirt ingestion. the ring end gap should be checked using new rings. 31). and rod assembly in the cylinder bore with the ring end gaps staggered. The second compression ring will have either an inside chamfer or an outside notch. AND CONNECTING RODS Piston
The piston should be checked for wear by measuring near the bottom of the skirt 90 degrees from the piston pin hole with a micrometer.

ARROW DIRECTION
32
MATCH MARKS
MATCH MARKS
33
BEVEL CHAMFER TOOTH CRANKSHAFT GEAR
34
CRANKSHAFTS AND CAMSHAFTS
Inspect the crankshaft visually and with a micrometer for wear. NOTE: Some OHH models used on chipper/ shredders may not require a compression release. oil dippers are attached to the bottom connecting rod bolt. the piston will have an arrow stamped on the top of the piston. (diag. Some engines have the oil dipper cast in the rod cap. the piston can be installed either direction on the connecting rod. The timing marks on the camshaft and the crankshaft gears must be aligned for proper valve timing.O. the mating crankshaft and governor gear should also be replaced. On all engine models. Clean the camshaft with solvent and blow all parts and passages dry with compressed air. and OVXL. or out of round condition at the bearing surfaces. scoring.T. Check for bends on the P. the match marks on the connecting rod and cap must align and face out when installing the piston assembly into the engine (diag. On OHV 13.5 . (diag. 33 & 34).CONNECTING RODS
Some engine models have offset piston pins (not centered) to centralize the combustion force on the piston. end using a straight edge. The rod bolts should be torqued in 50 inch pound (5. On engine models OVM. Consult the specification chart for the proper rod bolt torque when installing the cap.70 engines use serviceable MCR components and must be assembled as illustrated in "Assembly" with a thrust washer placed on the camshaft next to the compression release weight. 32) If the piston does not have an arrow.17 engines. scratching.130. On horizontal shaft engines.
CAMSHAFT GEAR TIMING MARK
PUNCH MARK SMALL HOBBING HOLE
35
CRANKSHAFT
Camshafts
Check the camshaft bearing surfaces for wear using a micrometer. CAUTION: NEVER TRY TO STRAIGHTEN A BENT CRANKSHAFT. Inspect the cam lobes for scoring or excessive wear. If a damaged camshaft is replaced. When installing the connecting rod to the piston it is imperative that the rod be installed correctly. 35 & 36). OHH and OHSK50 .65 Nm) increments until the specified torque is achieved. OHSK120 . OHM. making sure that the pins and counterweights are operating freely and smoothly on mechanical compression relief types. square or a dial indicator. The arrow on the top of piston or on the piston skirt must point toward the push rods or the carburetor side of the engine when installing it in the cylinder. an arrow is found on the piston skirt.
GEAR KEYWAY
CAMSHAFT GEAR
SMALL HOBBING HOLE
36
COMPRESSION RELEASE MECHANISM
37 71
. If the crankshaft gear is pressed on it is not serviceable and the crankshaft must also be replaced.

Using fingers. The engine will now run at full compression (diag. Consult the cutter's complete procedure guide for additional information. except those units that use extended camshafts which will continue to use a cast iron camshaft.Mechanical Compression Release (MCR) camshafts have a pin located in the camshaft. 38). or distorted they can be regrounded using a grinding stone or a valve seat cutting tool.249" (6. First.91 mm). which consists of three different cutters. and Neway #100-1/4 for the . resulting in lower emissions and reduced compression for easier pull starting (diag. to lift the valve to relieve the engine compression for easier cranking. The contact area or line should be continuous and appear on the upper 1/3 of the valve face. use the 60 degree cutter to clean and narrow the seat from the bottom to the center (diag. This camshaft is used on OHH/OHSK 50-70 engines that have been manufactured after DOM (date of manufacture) 7048.325 mm) exhaust guide. 40). Valve seats are ground to an angle of 46 degrees to a width of 3/64" (1. The ramp delays the intake valve closure. use the 31 degree cutter to clean and narrow the seat from the top toward the center (diag. Neway # 100-1/4-1 for the . It is CRITICAL that the new valve springs be installed or lobe damage will occur on the camshaft. This change that took place in February of 1997 and is basic on the OHH engines.250" (6.191 mm) (diag. The ramp is located on the backside of the intake cam lobe. pitted.
INTAKE
EXHAUST
39
The recommended procedure to properly cut a valve seat is to use the Neway Valve Cutting System.
BOTTOM NARROWING CUTTER 150 600 SEAT BOTTOM NARROWING SEAT 3/64" SEAT 460 310
TOP NARROWING CUTTER
TOP NARROW
SEAT CUTTER
310 460
40
41
BOTTOM NARROW
42
72
.35 mm) intake guide. 42). Some OVRM engines use a ramp compression release (RCR) system that works with the intake valve. 41). that extends above the intake or exhaust cam lobe. Check the contact area of a new or reconditioned valve face on a finished valve seat. The tapered pilots required are. OVRM and OHH engines have a small combustion chamber and require the use of a special Neway cutter #103 for the 46 and 31 degree combination cutter.
CAMSHAFT COMPRESSION RELEASE
COMPRESSION RELEASE SPRING
THRUST WASHER A INSERT SPRING END "A"
B
38
Valve Seats
Valve seats are not replaceable. Third. The 60 degree cutter is Neway cutter # 111. Re-cut the seat to move the contact area higher or lower if necessary and recheck the contact area. use the 46 degree cutter to cut the seat to a width of 3/64" (1. NOTE: You must install the thrust washer between the cover and cam to prevent wear. Some OHH engines use a composite camshaft. centrifugal force moves the weight outward and the pin will drop back down. If they are burned. A camshaft kit replaces the old camshaft and includes compression release components and two light tension valve springs. When the engine starts. 39). Second. snap the valve sharply against the corresponding valve seat and view the line imprinted on the valve face.

Using a pliers. Submerge the head in a container of oil so that the valve guide bores are completely covered with oil. Using a 1/2" (12. Place the valve guides in a freezer for an hour or longer to ease assembly.794 mm) oversize or be replaced as service parts. 6" (15. 5. BE CAREFUL ! THE HOT OIL AND HEAD CAN EASILY CAUSE BURNS. push the guide out of the head with the arbor press.2040C).130. CONSULT PARTS MANUAL)
1. Carefully drain the excess oil out of the head. Quickly work the next two steps while the head is hot to prevent pressing the guides out with the head too cool. OHSK80 . mark the lifters to install the lifter in the same position as it was removed from. The upper and lower valve spring caps must be redrilled to accommodate the oversize valve stems.24 x 30. the valve seats must be recut to align the valve seat to the valve guide. Oil temperature must be 375 o . Install the snap rings on the new replacement valve guides.400oF (1900 2040C). CAUTION : USE PROTECTION FOR EYES AND HANDS. they can be reamed oversize to accommodate a 1/32" (. NOTE: DO NOT USE A STEEL HAMMER TO SEAT THE NEW GUIDE. Submerge the head in a container of oil so that both guides are completely covered with oil. 6.
VALVE GUIDE INSTALLATION
1. Place the head on the bed of an arbor press on parallels with the snap rings on the long ends of the guides facing down. Insert the new guides in the head with the long end of the guides up. 4.794 mm) oversize valve stem. Visually check the lifter for wear on the cam contact surface and push rod contact surface. All other overhead valve engines have valve guides that are permanently installed in the cylinder head. 4.7 mm) diameter. Refer to the "Table of Specifications" (Chapter 10) to determine the correct oversize dimension. 73
. Heat the oil on a hot plate approximately 1520 minutes until the oil begins to smoke. remove the head from pan of oil.
VALVE GUIDE REMOVAL (WHERE APPLICABLE. Reamers are available through your local Tecumseh parts supplier. It may be necessary to use a rubber or rawhide mallet to fully seat the new guide to the snap ring. Carefully drain the excess oil out of the head.24 cm) drift punch located in the center of the old valve guide.VALVE LIFTERS
When removing the lifters. If the guides get worn excessively. CAUTION : USE PROTECTION FOR EYES AND HANDS. Place the head on a 6" x 12" (15. BE CAREFUL ! THE HOT OIL AND HEAD CAN EASILY CAUSE BURNS. Using a pliers. 3. After oversizing the valve guides.5 cm) piece of wood with the head gasket surface down. and OVXL have valve guides that can be reamed 1/32" (. 2. 2. The valve lifters may be slightly different lengths. The guides should be reamed oversize with a straight shanked hand reamer or low speed drill press.
GUIDES HEAD
OIL HOT PLATE
3.
VALVE GUIDES
Engine models OVM. Allow the head to cool and re-cut both valve seats using a Neway cutter to align the new guides to the valve seats. Quickly work the next two steps while the head is hot to prevent damage to the guides or the head. OHM. GUIDE OR HEAD DAMAGE WILL RESULT. Guides removed too cool will permanently damage the head HEAT UNTIL OIL BEGINS TO SMOKE 43 by removing aluminum necessary to hold the new guides in place. Do not allow the drift punch to contact the head during this step. remove the head from pan of oil. Heat the container on a hot plate approximately 15-20 minutes until the oil begins to smoke. 5. Consult the tool section in Chapter 11 for the correct part numbers. Oil temperature must be 375o .400oF (1900 .

Plate. 45). Most engines have the breather tube connected to the air cleaner assembly (diag. align the reed valve and plate parallel to the top surface of the breather opening in the crankcase. If the plate has a notched corner. OHH engines use an umbrella valve type breather that is found in the rocker arm cover.5 . A new breather tube boot is recommended for replacement to assure proper crankcase seal.O. Use solvent and compressed air to clean the area if necessary.Screw 4 . Limit 3 .Baffle/Gasket 5 . Be careful not to drop the breather body out of the rubber boot when removing (diag. install the plate with the mark facing out.17 engines. Mark or note the location of the breather tube. Clean the internal element or reed area with solvent and compressed air if necessary.CRANKCASE BREATHERS
The breather element and case can be cleaned using cleaning solvent. the drain holes must be open and be on the bottom.Valve.T. The umbrella check valve allows positive pressure to be vented through the element and out the tube. If the plate is marked. Apply engine oil to the breather tube boot and push the breather in until the top shoulder of the boot contacts the crankcase. 44). Reed 2 . Hold the reed valve and plate in this position while tightening the screw. Use a large flat blade screwdriver to pry the boot up and lift the breather assembly out.
44
45
GASKET COVER BODY REED BODY
Side Mounted Breather
This type of breather mounts over the valve compartment and uses a reed style check valve.
2 1 4 5
FILTER DRAIN HOLE GASKET COVER TUBE
46
BREATHER OUTLET TO CARB UMBRELLA
47
3
1 . install the notch toward the P. Late production OVRM engines use the rubber boot and breather tube as a "pop in" design. side of the engine. Individual components are serviced only by the replacement of the complete cover. On OHV13. When installing.Cover
48
49
74
.
ELEMENT BAFFLE OIL RETURN PRESSURE OUT
TUBE
CHECK VALVE
Top Mounted Breather
This type of breather is mounted in the top and rear of the cylinder block in vertical shaft engines. Make sure the small drain hole or holes are clean and installed down to allow return of oil back into the crankcase.

Measure the bearing surface diameters using a micrometer and check the specifications for worn or damaged parts. If the crankshaft is removed from the engine.
OIL SEAL REMOVER TOOL: POSITIONED FOR REMOVAL OF OIL SEAL OIL SEAL
50
OIL SEAL DRIVER 670272
OIL SEAL
OIL SEAL DRIVER PROTECTOR
CRANKSHAFT BEARING SERVICE Ball Bearing Service
Remove the two bearing retainer screws and washers. remove the seal by using the proper oil seal puller (diag. CHECK TO SEE IF THE SEAL IS RAISED OR RECESSED. lbs. except oil seal replacement.0 Nm) of torque. Always use new gaskets and new oil seals installed using seal protectors after the cover is removed. ATTEMPTING TO INSTALL THE SEAL TOO FAR IN CAN CAUSE DAMAGE TO THE OIL SEAL AND ENGINE. looking for wear and scoring of the bearing surfaces. 50). Place the oil seal over the protector and place it over the crankshaft.
Cylinder Cover
Clean and inspect the cover.
Oil Seal Service
NOTE: BEFORE REMOVING THE OIL SEAL. require the engine to be disassembled. See "Engine Disassembly Procedure" in this chapter. Select the proper seal protector and driver from the tool list in Chapter 11 to install a new oil seal.
SNAP RING
51
OIL SEAL REMOVED
52
75
. OIL SEAL. 670272.CYLINDER COVER. remove the old oil seals by tapping them out with a screwdriver or punch from the inside. When reinstalling the cover. Drive the seal into position using the universal driver part no. Install a new ball bearing by pressing the bearing from the inside of the cover toward the outside until the bearing contacts the shoulder. 51). Install the two bearing retainer screws with washers and tighten to 45 in. (5. If the crankshaft is in place. The seal protector will insure that the seal is driven in to the proper depth (diag. Remove the ball bearing in the cylinder cover by pressing the bearing from the outside of the cover toward the inside using an arbor press. TAP IT INTO POSITION GENTLY UNTIL IT IS SEATED INTO ITS BOSS. WHEN INSTALLING A NEW OIL SEAL. SOME SEALS ARE NOT POSITIONED FLUSH TO THE CYLINDER COVER. AND BEARING SERVICE
The following procedures. Replace as necessary. apply a drop of Loctite 242 to the cover screw threads and torque the cover screws to the recommended specification.

.....413 mm) 31462 .. rings.
MATCH MARKS DURLOCK BOLT OIL SEAL PROTECTOR
53
54
76
.25............0000 ............. it requires line reaming to the proper size..8755 ..........1...... After the bushing has been installed....................... 1....3765 .................. Using the correct seal protector (see Chapter 11 under "Tools").... apply engine oil to the crankshaft bearing surfaces and insert the tapered end of the crankshaft in the crankcase.. 1. Align the match marks on the rod cap and rod....4 ....3770" (34..........226 ...............976 mm) 35400 .....976 mm)
ENGINE ASSEMBLY
The following procedures apply to most engine models... 1..........413 ..22......25.......413 mm) 31546 .34....34........... 2..... Use new gaskets and seals at all locations........0000 .........0005 ................0005" (25............ Push the piston assembly in until the rod is positioned on the crankshaft rod journal surface.. Slide the crankshaft in until it bottoms......................................................1.......3765 . stagger the ring end gaps..250 mm) 31461 .1....1.................................. 1. connecting rod bearing surface..1....... 3....25...950 ............1880 ...0010" (25..0005" (25. Actual procedure may vary.... compress the rings......... and push the piston assembly into the cylinder with the match marks on the connecting rod facing out of the crankcase and the arrow on the top of piston or on the piston skirt pointing toward the push rod location or the carburetor side of the engine if applicable...1.....................413 mm) 33368 .. Clean all internal engine parts with solvent and blow dry with compressed air or allow to dry. 1.......175 ..4 ...30.0005 ...... Using a band type ring compressor........413 ... 1.................... 1..1890" (30...0010" (25. 1.. have a reputable machine shop do this work for you...8760" (22..........25............ Apply engine oil to the piston skirt...............................3770" (34.....1.425 mm) 34837 . 1...............0000 ....1.SERVICE BUSHING
We are supplying this bushing for service repair. install the rod cap bolts and dipper if applicable and tighten the bolts in equal increments to the specified torque.... ...................0005" (25..... Following the chart below........950 . 4...............25..... and the cylinder bore...4 .425 mm) 35377 ....2 mm) 34836 .........
BUSHING SIZE CHART BUSHING SERVICE PART NUMBER FINISHED REAM BORE DIAMETER
30979 ........

NOTE: Engines equipped with rotary oil pumps must have the drive shaft and pump assembled after the sump cover is installed. barrel and plunger style oil pump (chamfered side toward the gear) if applicable. Align the timing mark or notched tooth on the crankshaft gear to the mark or hole in the camshaft gear. Some OHV11 . and slide the release pin in the small hole near the center of the cam gear. CRANKSHAFT MATCH MARK THINNER GEAR THICKER GEAR
COMPRESSION RELEASE
CAMSHAFT
COMPRESSION RELEASE SPRING
THRUST WASHER INSERT SPRING END "A" A
B
55
GASKET OIL PASSAGE GASKET SCREW
OIL PUMP SHAFT
OIL FILTER OIL PUMP ASSY. (diag.C. "O" RING OIL PUMP COVER OIL PASSAGE COVER
SCREW CHAMPFER UP TOWARD CAM
56
DUAL SHAFT COUNTERBALANCE
57
CAM TIMING
a. Dual Balance Shaft Time the dual shaft counterbalance system with the piston at T. If the engine is not equipped with a filter.
58
ULTRA-BALANCE® TIMING
59 77
.17 engines come equipped with a spin on oil filtration system. Install the lifters. Assemble the compression release components to the camshaft on engine models OHH and OHSK50-70. Assemble the thrust washer on the camshaft next to the compression release.D. Install the counterbalance with the thicker gear in the far right boss in the crankcase and the other counterbalance shaft with the thinner gear in the far left boss while aligning the timing marks. time the Ultra-balance® with the piston at Top Dead Center (T. ultra-balance shaft or dual balance shafts if applicable. If equipped. 55) NOTE: Some OHH models used on chipper/ shredders may not require compression release mechanisms.5. Install spring end "A" through the release from the pin side.D. insert spring end "B" through the camshaft gear. one may be added IF THE SUMP HAS AN OIL PASSAGE COVER.). 7. Slide the drive gear over the keyway in the crankshaft while aligning the timing mark with the thicker counterbalance gear. The kit part number 36435A should be ordered to upgrade the engine if desired. 6. Slide the drive gear over the keyway in crankshaft while aligning the timing marks on the gears. camshaft.C.
DRIVE GEAR.

5 . Mount the cylinder cover or flange with the governor gear assembly installed to the crankcase using dowel pins to position the cover and a new gasket. OVM.8 Nm) torque. On OHV 13.1 mm) of the stud is exposed.8. followed by the retaining ring. place the springs (dampening coils toward the head) over the valve guide and place the valve caps on the springs with the larger opening away from the springs. Do not force. 10. 65 on page 79). Apply engine oil and install the oil pump ring and rotor. Apply a drop of blue Loctite 242 to the cover screw threads and tighten to the specified torque. Tighten the head bolts in the numbered sequence using 60 inch pound (6. followed by a new "O" ring and the pump cover. For models OHH and OVRM. 9. install a thrust washer (if applicable) over the crankshaft. For OHV models. never only lap the seats.5 -17 engines. Tighten the screws to 50-70 inch pounds (5. Repeat the procedure for other valve. install the springs (dampening coils toward the head) and retainers on the valves and use fingers to compress the springs until the notch in the retainer is located in the notch in the valve stem. place the push rods in the block before installing the head and head gasket. install the oil pump drive shaft into the slot in the end of the camshaft. Install the cylinder head using a new head gasket. On OHV 11-13 models. Compress the spring and install the valve retainers to lock the valve to the valve cap. and either turn the stud in or secure with a locking nut as shown so about 1-1/2" (38. Install the cover down onto the crankcase and slightly rotate the crankshaft to allow the governor gear to mesh. Use spring compressor tool part # 670315A installed on a rocker arm stud. NOTE: Always cut the valve seats. Install the breather assembly. On engines with ball bearings in the cover. 78
RING
SHAFT
ROTOR
ROTARY PUMP
60
NOTE: INSTALL OIL PUMP AFTER THE SUMP IS ON
61
62
RETAINERS HELD BY SPRING TENSION AGAINST THE CAP RETAINER
CAP
VALVE SPRING COMPRESSOR TOOL PART NO. Repeat the procedure for other valve. OVXL (diag. Use a small block to support the valves tight to their seats while placing the head on a flat surface. 11. Replace all "O" ring and gaskets in kit. 670315
63
. NOTE: Tecumseh strongly recommends you order a complete seal kit.8 Nm) increments to the specified torque. Pre-assemble the valves and spring assemblies into the cylinder head on all engine models EXCEPT OHM. Rotate the crankshaft to place the piston at Top Dead Center (TDC) on the compression stroke. OHSK80-130.

Use lubricated new "O" ring seals for both ends of the push rod tubes and install the push rod tubes in the crankcase.
OVM / OHM STYLE
65
d. a.292 mm) ALL OTHERS THIS END MUST FACE TOWARD THE STATIONARY PART OF THE ENGINE (CYLINDER HEAD) OVRM/OHH 1.
DAMPENING COILS LOCATED CLOSER TOGETHER FREE LENGTH 1. 66). 670315
f. Compress the valve spring with the tool and insert the two retainers into the keeper so the inside ridge of the retainer locks into the valve stem groove.
66
79
.5 cm) piece of fuel line and wedge one end on each side of the valve stem through the port opening to hold the valve. Install the rocker arm housing.
VALVE SPRING COMPRESSOR TOOL PART NO. new rocker arm studs with "O" rings under the guide plate. Use a 12 inch (30. g. OHSK120. Install the push rods with the cupped ends of the rods placed on top of the lifters. Install the valve box to head retaining screw using a flat washer and a new "O" ring.
RETAINERS HELD BY SPRING TENSION AGAINST THE CAP RETAINER
CAP
e.105 (28. valve springs with the dampening coils toward the head. 64) and valve spring retainers with the larger opening away from the engine. Visually check correct placement through the valve box opening. Install the valves into the head.067 mm)
64
(BLACK)
b. CONTINUE WITH STEP 13 FOR CURRENT PRODUCTION MODELS. Repeat the procedure for the other valve (diag. Install the new o-rings (white o-ring on the exhaust guide) followed by valve spring caps. and using a new head gasket. Tighten the head bolts in the numbered sequence using 60 inch pound (6. place the head on the cylinder block.
TEFLON EXHAUST (WHITE) "O" RINGS
c. push rod guide plate with the legs facing up.980" (50.12. NOTE: TORQUE THE CYLINDER HEAD FOLLOWING THE SEQUENCE ON PAGE 69. Lift each valve up until it contacts the seat and hold the valve in this position. OVM AND OVXL. (diag. Bolt the valve spring compressor tool part # 670315A on a rocker arm stud using the rocker arm bearing and locking nut (diag. 66).8 Nm) increments to the specified torque. STEPS 12A -12G APPLY ONLY TO EARLY PRODUCTION ENGINE MODELS OHM. Tighten the screw and the studs to the specified torque.

3/16" ALLEN WRENCH
7/16" CROWFOOT WRENCH
OHH / OVRM
67
LOCKING / ADJUSTING NUT CROWN DOWN "O" RING OR GASKET
FEELER GAUGE
VALVE STEM
ROCKER ARM STUD OVM / OHM / OVXL
PUSH ROD GUIDE TABS UP
68
7/16" SOCKET WRENCH
1/2" CROWFOOT WRENCH
OHV 11-13 and OHV 110-135 / OHSK80-130
69
80
. (13.13. Rotate the crankshaft at least one full turn to check push rod movement and valve lash (diag. Insert the push rods in the lifter sockets with the longer steel end toward the rocker arms. Turn the screws in until slight play exists between the valve stem and rocker arm. install the guide plate with the rocker arm studs and torque to 190 in. place the rocker arms on the rocker arm screws followed by the locking nut. OHSK80-130. lbs. and rocker arms and lock nuts on the rocker arm pivot screws. A 7/16" crowfoot will be needed to torque the lock nut.5 Nm) of torque. OHV110-145 models. and both valves closed. lbs (13. install the push rods on the lifters. Rotate the crankshaft at least one full turn to check push rod movement and valve lash (diag.5 Nm).5 Nm) of torque. Tighten the adjusting nut until slight play exists. Place the rocker arms onto the studs with the socket end toward the push rod and thread the rocker arm bearings on until excessive play is removed. washer. (21. OHV110-145. rocker arm bearings. with a 1/2" crowfoot. Rotate the crankshaft at least one full turn to check push rod movement and valve lash (diag. lock this position by holding an 3/16" Allen wrench on the pivot ball screw while tightening the lock nut to 120 in. Fasten the screw to the head with the push rod guide plate tabs facing up. OHSK120. On OHV 11-13. OVM. On models OHH and OVRM. and push rod guide plate (with the tabs up). install the rocker arms. lbs. (2 Nm). the piston at T. and OVXL models. tighten down the rocker arm studs to 190 in. On OHV13.. and new rocker arm adjusting nuts on the studs.5 Nm).D. lbs. OHSK80-130. Insert the specified feeler gauge between the rocker arm and valve stem. On engine models OHH and OVRM. OHM. hold the rocker arm pivot bearing using a 7/16" wrench or socket while using a 1/2" crowfoot to tighten the lock nut to 120 in. Set the valve lash with the engine cold. On models OHV 11-13. On models OVM. 67). Adjust the rocker arm hex nut with a 1/2" wrench to set the correct valve lash and tighten the locking jam nut to 18 in. 69). Adjust until a slight sliding drag is felt. lbs. install the push rods on the lifters. Turn the screws in until slight play exists between the valve stem and rocker arm.5 -17 models. (21. On OHM. OHSK120 and OVXL. 14.C. 68).

70). 19. Connect the breather hose to the valve cover fitting on model OHH. Current production models OHV135 . 71). carburetor.7 Nm).3175 mm) air gap tool between the flywheel magnets and the laminations of the module (diag.On models OHV 135 .0125" (. Install the ignition module using a part # 670297 . Attach the ignition ground lead to the module terminal.175
5/32" ALLEN WRENCH
1/2" WRENCH
70
1/2" WRENCH
71
. Check the governor and speed control hookup and adjustment . starter cup (if applicable). 72). 15. 20.175 use a 1/2" wrench to tighten the rocker arm bearing to the correct valve lash. (8. Rotate the crankshaft one full turn to check push rod movement and correct valve lash (diag. Once adjusted use a 1/2" socket and torque the jam nut to 130 inch pound (14. flywheel key. Rotate the crankshaft at least one full turn to check push rod movement and valve lash (diag. Install the blower housing on all engines with the speed control mounted on the blower housing or engine block. bevelled washer (concave surface in). and check for contact while rotating the flywheel. and air cleaner assembly while hooking the throttle and governor linkage.3175 mm) AIR GAP
72
81
. 16. Attach the alternator coil if applicable and route the wires away from the flywheel area.175 hold a 1/2" wrench on the rocker arm bearing while tightening the 5/32" Allen head set screw to 75 in. and attach the ignition groundout lead at the control if applicable. 21. remove the tool. Install the rocker arm cover using a new gasket or o-ring and tighten the screws to the specified torque. speed control. Install the flywheel spacer if applicable. Use strap wrench part # 670305 to hold the flywheel and tighten the nut to the specified torque. Tighten the mounting screws.0125" (. Attach the governor arm lever if removed. lbs. 17.5 Nm) of torque. and flywheel nut. Install the blower housing on all engines with intake pipe mounted speed control brackets. 18.see Chapter 4 under "Service". Install the intake pipe. None should be found. Attach the backing plates or baffles. flywheel.
1/2" TORQUE WRENCH OHV135 .

25. Slide the fuel line on the carburetor fitting and secure with a clamp.E. NOTE: If the tank is supplied by the O.
REMOVE BOLTS
SLIDE TANK
73
82
. Optimize the carburetor if adjustable. Tecumseh's tanks have a fuel filter in the tank and service is not necessary. Mount the engine to the equipment and connect wiring and control cables. Install the spark plug and high tension lead. replace the fuel filter. 23. 24. Start the engine and allow it to run approximately five minutes to reach operating temperature. Slide the breather tube on the carburetor or air cleaner fitting if applicable. verify top no load and idle RPM settings. Attach the fuel line and secure with clamps. 26.M. OVRM rotary mower engines require the blade to be secured to the blade hub adapter and crankshaft before attempting to start the engine. Add fresh fuel to the fuel tank and secure the cap.22. Fill the engine with oil to the full mark on the dipstick. Attach the fuel tank (if applicable) using bolts or wedging the tank in the blower housing slots provided.

ENGINE SPECIFICATIONS AND SEARS CRAFTSMAN CROSS-REFERENCE The engine specifications listed on the following pages include tolerances that are considered acceptable to achieve normal engine operation. Observed values inside the listed tolerance range are satisfactory and require no adjustments.

Note A: OVRM60, 21000 spec. numbers with a "B" suffix and all OVRM 65, 22000 spec. numbers have a displacement of 11.9 (195.04). Note B: All OVRM 60, 21000 spec. numbers with a "B" suffix and all OVRM 65, 22000 spec. numbers have a 2.795"/2.796 (70.993/71.018) Bore. Note C: All engines equipped with a ball bearing will have "0" End Play.

Note A: OVRM60, 21000 spec. numbers with a "B" suffix and all OVRM 65, 22000 spec. numbers have a displacement of 11.9 (195.04). Note B: All OVRM 60, 21000 spec. numbers with a "B" suffix and all OVRM 65, 22000 spec. numbers have a 2.795"/2.796 (70.993/71.018) Bore. Note C: All engines equipped with a ball bearing will have "0" End Play. Note D: For OHSK110 models with specification number starting with 223000 have a displacement of 21.82 ( 357.63 cc).

SPECIAL TOOLS BOOKLET 694862 This booklet depicts all specialty tools offered by Tecumseh which can be used on 2 and 4 cycle engines and Peerless units. Covers identification of carburetors used on Tecumseh engines and how to troubleshoot and repair them. 695578 Covers the diagnosis and repair of the Vector Series. (Tests are similar for 98. 691218 Covers the diagnosis and repair of Peerless® power train components. Except the TC Engine and TVS840. Illustrates time saving features incorporated into the manual. This booklet is designed to be used as a work bench quick reference guide when servicing Tecumseh engines and motion drive systems. possible problems and related repair procedures of Tecumseh Ignition Systems. SPECIAL BOOKLETS INSTRUCTIONAL GUIDE 692738 Assists in the use and understanding of the Tecumseh Master Parts Manual. 2-cycle engines. 2-cycle engines. VHS only. 695555 Spanish Covers the diagnosis and repair of the Tecumseh 4-cycle light/medium frame engines. 692509 Covers the diagnosis and repair of the Tecumseh 4-cycle light/medium frame engines. 695657 German Covers the diagnosis and repair of the Tecumseh 4-cycle light/medium frame engines. QUICK REFERENCE CHART BOOKLET 695933 This booklet contains the quick reference information found on Tecumseh wall charts. 695148 Teardown and reassembly of the 900 series transaxles. 88 695185 Electrical Troubleshooting. 694530 Test procedures for Tecumseh electrical components using Merco-O-Tronic Tester 9800. 695562 French Covers the diagnosis and repair of the Tecumseh 4-cycle light/medium frame engines. VHS only. 695285 An in-depth look at the 800 series transaxles. This video will show a complete step-by-step procedure for teardown and reassembly of the 900.)
. EDUCATIONAL MATERIALS AND TOOLS
AVAILABLE TECHNICIAN'S HANDBOOKS 692508 Covers the diagnosis and repair of Tecumseh 2-cycle engines. 910 and 920 series transaxles. HH100. Explains new carburetor parts breakdown format. IGNITION SYSTEMS TROUBLESHOOTING BOOKLET 694903 This booklet contains information on the identification. VIDEO PROGRAMS 695015 Carburetor Troubleshooting. 98A and 79. 691462A Covers the diagnosis and repair of Tecumseh 4-cycle large frame engines. 694988 Contains diagnosis and technical information for the repair of TVS840. HH120. 801 and 820 transaxles. OH120-180 Model numbers are located on the engine shroud. 4-cycle engines. CARBURETOR TROUBLESHOOTING BOOKLET 695907 This booklet is designed as a quick reference to carburetion problems and related repair procedures. HSK/HXL845/850. 695244A Covers the diagnosis and repair of the OVRM/OVM/ OHM/OHV 4-cycle overhead valve engines. Detailing the teardown and reassembly procedures for the 800.CHAPTER 11. TESTER BOOKLETS 694529 Test procedures for Tecumseh electrical components using Graham-Lee Tester 31-SM or 31-SMX-H. 695059 Understanding Tecumseh Ignition Systems. This video training program will assist the small engine technician in the proper procedures for troubleshooting electrical systems on outdoor power equipment. A basic program designed to give the small engine technician first hand knowledge of Tecumseh ignition systems so the technician can understand the system and perform repairs to it. VH100. 694782 Contains technical information for the repair of the TC series. AVAILABLE FOREIGN TECHNICIAN'S HANDBOOKS 694732 Spanish This manual covers the following models: VH80. 4-CYCLE ENGINE FAILURE ANALYSIS 695590 This booklet is designed as a tool for the average technician to correctly assess the cause of failure. HH80.

and 4-cycle engines.TOOLS TOOL KIT 670195E Kit contains tools for 2.
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. Includes all items on this page but items may be purchased separately.